+3  A: 
  1. Firefox
  2. Notepad++
  3. Python
  4. Some music (it calms me between coding jobs!)
Salty
+16  A: 

I like PortableApps. I use NotePad++, OpenOffice applications, etc.

jrcs3
A: 

PortableApps as well. I played with a few Linux-on-a-sticks, including Slax (it's a great little distro!), but the computers at my school don't seem to allow booting from USB anymore :'(

I also managed to get Cygwin on my USB, but it's a little weird, and I don't use it often. Eclipse as well, but only if you absolutely need it, it runs slows as molasses.

HappyCodeMonkey
+1  A: 

apache, php5 and mysql (as well as notepad++)

I also have some scripts that copy the php.ini file to the C:\windows folder,etc.

cbrulak
How do you install Apache/MySQL to a portable drive? This sounds interesting.
thomasrutter
I copied the contents of c:\program files\Apache Group to the thumb drive. I also have a batch script which launches the server:start cmd.exe /k "%DEV_KEY_DRIVE%\Apache Group\Apache2\bin\Apache.exe"
cbrulak
Or you can use XAMPP http://apachefriends.org/xampp
Lucas Jones
+3  A: 

It's handy to have http://unxutils.sourceforge.net/ (grep/cut/sh etc...) You may need some environment better then cmd to run it. Try FAR - http://www.farmanager.com/index.php?l=en (use open source one).

Denver is all in one web server package (also with usb-flash install support): http://translate.google.com/translate?hl=uk&ie=UTF-8&u=http%3A%2F%2Fwww.denwer.ru%2F&sl=ru&tl=en&history_state0=

But it is for russian audience.

Also: http://www.makeuseof.com/tag/portable-software-usb/

Malx
+1  A: 

My VPN Client Software ;)

MMmm Sweet sweet remote desktop. drool

Kieveli
+1  A: 

I was about to say: "Nothing" and I decide to double check my USB and I found VIM and my .vimrc and ProcessXP

I don't usually use it from there, but from time to time ( 3 -6 months ) I get into a new machine and copy them from the usb.

OscarRyz
I change my vimrc too regularly. I am thinking about putting it in source control.
thomasrutter
+1  A: 

Ones not mentioned:

  • WinSCP (for all your S/FTP, etc connections)
  • LINQPad (for all your .NET code testing)
  • PuTTY
Slace
+4  A: 

Ubuntu Linux

Mark A. Nicolosi
+1 - if you want to carry development tools with you, why not an entire development environment? I have Kubuntu installed on an 8G thumb drive, and it's sufficiently performant for the environments where I find myself booting it up
kdgregory
+1  A: 
  • Strawberry Perl, I had to edit some batch files to use the USB e: instead of the hard drive c:
  • MinGW, for GCC, G++ and added GDB, maybe MSYS when I get around to it
  • MSVC6, just for console apps so far, haven't tried to include MSDN
  • Codelite, for an IDE, better than Code::Blocks and lighter than Eclipse
  • Ultraedit v9, more recent versions are too bloated and slow, and probably don't run from USB
  • Quite a few other utilities that come in useful, e.g. grep, ssed, batch files to setup environment variables and start Perl, GCC or VC, etc.
Rob Kam
+11  A: 

For Windows, many of the sysinternal tools.

TheSoftwareJedi
I would be lost without Process Explorer and Autoruns on any stranger's system, especially when I'm trying to "fix" their "slow starting" problems.
thomasrutter
+3  A: 

PortableApps.com has most of what's on my portable USB drive:

  • Filezilla
  • Firefox
  • Notepad++
  • PuTTY
  • Wireshark

Besides those, I also have Beyond Compare on my USB drive.

jeffl8n
A: 

The XamppLite Web-Server so I can be able to work and test any PHP, CGI or scripts wherever I go.

Andreas Grech
+3  A: 

Note: I am a Windows developer. This colours what you read below.

  • Dependency Walker (Depends.exe)
  • WinZip
  • Notepad++ (v5)
  • DbWin32
  • Process Explorer
  • HEdit - a hex editor
  • WinDiff
  • Ripper - an app I co-wrote for stripping redundant lines from log files.
  • DelSub - an app I wrote for deleting files with given extensions in a folder tree. Handy for removing NCBs and PCHs etc. before backup.
  • DosHere - an explorer extension for adding a "command prompt here" entry to the context menu for any folder. This is the FIRST THING I put on any windows box I have to use.
  • DeTab - an app I wrote for stripping tabs out of source files. Note to self - need to update this for Unicode.

Note the emphasis on debugging native code here, because if I'm out in the field, that's usually what I'm doing.

Bob Moore
I'm a WinMerge guy myself, but I like your style.
John Dunagan
winRAR! Its the new millennium!
icelava
+1  A: 

I would add to the list this great OSS for Windows:

  • 7-zip. It can handle not only zips, gzs, bz2s, rars or arjs but even rpms or isos.
  • Winmerge. A directory/file comparation tool is always necessary.
Fernando Miguélez
A: 

Mine just has music, and my GTD projects. Oh, and a couple of games for those in-between times ;-)

Graham Lee
+1  A: 
  • Putty
  • WinSCP
  • Notepad++ - a must have.
  • Firefox - another must have.
  • XAMPP - there is a standalone version especially for memory sticks which works well.
  • Netbeans
Mark Davidson
A: 

I have a full install (persistency broke on the LiveUSB version) of Fedora 9 (Sulphur) on one partition (ext2 so Windows can't see it) with the following tools:

And on the other partition, my data and the following Windows tools:

EDIT: I now have Fedora 10. Slightly slower, and needs vga= for the new boot to work, but the new features make it worth it.

Lucas Jones
A: 

One of my USB Flash drives has the books I bought in PDF format from Safari Online. The ability to carry ten or twenty books about .NET, HTML, CSS, SQL, Active Directory, Security, WPF, or whatever else I happen to have in there, and pull it up without breaking my back is PRICELESS.

Another has NUnit, TestDriven.NET, WinMerge, the scrollbar fix for VB6, AnkSVN, a copy of the C# specification, and a couple of homebrew tools.

Mike Hofer
A: 

When I get around to it, I'm putting the Windows Home Server PC Recovery image on a USB drive. Not only is it nicer than CD for recovering a home server CD, but you can also boot to a CMD prompt or run disk manager.

I prefer not to cache copies of downloadable software, since downloading anew often brings the latest updates. The exception is software I have to jump through hoops to get (registration, etc.)

Jay Bazuzi
A: 

I have my mobile phone number as the USB drive name so if I lose it an honest person could call me and return it.

AndyM
A: 

In addition to most tools already listed...

Process Explorer
Process Monitor
AutoRuns
Expresso
KeePass
ReNamer
TrueCrypt
Gordon Bell
A: 

For Windows:

  • PuTTY (PuTTY tray)
  • Xming - X11 server
  • tightvnc.exe

These let me access Linux systems where the real development tools live via SSH and VNC.

jtimberman
+1  A: 

I'm surprised JGsoft's excellent suite of tools hasn't been mentioned yet, particularly considering the author is one of us:

  • EditPad Pro (IMO, the best damn text editor there is)
  • RegexBuddy (the regex debugger)
  • PowerGREP (may not be vital if you're carrying Cygwin around, but it's more featureful than "real" grep and has a nice GUI to boot)

Sure, none of them are free, but they're sanely licensed and all of them support portable installation.

Ben Blank
I use an older (postcard-ware) version of EditPad every day. It's the first thing I install on a new computer!
Slapout
A: 

I go nowhere without puretext.exe. It's just a 28 Kb executable that gives you under Windows+V (or whatever key you want) what I would otherwise be doing quite often manually after hitting Ctrl+C somewhere:

  • Windows+R
  • N, O, T, E, P, A, D (if needed, often was still in my Run dialog...)
  • Enter
  • Ctrl+V
  • Ctrl+A
  • Ctrl+C
  • Alt+F4
  • N (for No)
  • Alt-Tab (correct number of times needed, if any...)
  • Ctrl+V

In other words: it pastes "pure text" from the clipboard, without any of the markup that might have been copied onto the clipboard with the text.

Any PC I work on for more than an hour - where I have permissions to get puretext.exe onto and running - I put it in C:\WINDOWS\, double-click it once, set it to autostart in its settings and always hide the icon in the task bar.

It is so worth it. ;-)

peSHIr
I have no idea what this app does, even after reading your description.
Beska
It pastes text from the clipboard as plain text, without any markup. In other words: the same you would get if you opened Notepad, pasted into that, select everything, copy it again to the clipboard and then paste into the actual destination. I'll edit my reply to elaborate.
peSHIr
+2  A: 

I carry a VirtualBox hard drive file that contains the whole development environment for our project.

It takes about a minute to set up on a any new machine for development in a familiar environment.

Install VirtualBox, create a new virtual machine, plug in the usb drive, point the virtual machine to the hard drive file, boot into the dev environment from the virtual machien. Takes about a minute atop of the download time of VirtualBox.

Nick
Interesting solution, I like it. Would probably need a relatively large USB drive I guess (4GB at the minimum?)
thomasrutter
I've been using this approach for a couple of months now. Here are some additional observations:Make your VM drive large (14 gigs here so it fits on the 16 gig stick); resizing VM drives is a b*tch and no 8 gigs is NOT enough, you will run out. How much space is used on your dev box by IDEs etc.? You get the idea.Needless to say, speed of the drive matters. You can also copy the VM image to the HD before you boot the VM. Which brings me to...Treat any specific VM image as completely disposable. This means check in or otherwise "shelf" your progress at a remote location, religiously.
Nick
A: 

Currently: Python + Python Stackless Lua JCreator ConTEXT

Most of my USB is made up of Installers/Source code though :)

Dalin Seivewright
A: 

I have to have Directory Opus on my USB drive. I use it primarily for the search feature, which is so much better than what Windows provides.

Also, Keepass, already mentioned here.

Mike Strother
+19  A: 

Sysinternals tools

JoshBerke
+21  A: 

Assuming a Windows Machine:

kgiannakakis
A: 

If you have room for it, AutoPatcher (you run it on your PC to download all the windows updates available, then take it to their place and use it to patch their Windows installation).

+3  A: 

When I am debugging something on someones' machine, the first thing I do is install Vim. Join us, it's a way of life.

Cannonade
May I add that we have cookies?
LuRsT
A: 

A debuggin Tool or a Profiler.

Geek
+1  A: 
  • emacs
  • tucan (for windows backups)
  • putty
  • winscp
  • SVN repository
Nuno Furtado
+1  A: 

MemTest if it's hardware troubleshooting?

Richard
+2  A: 

grep, definatly gotta have a grep tool of some kind.

Muad'Dib
Or my new favorite, ack: http://betterthangrep.com/
Don Wakefield
+2  A: 

I recommend WinDbg.

BobbyShaftoe
A: 

I can run Delphi5 on my USB, using some custom script to properly setup registry. It's pretty handy since it allow me to:

  1. Debug (Assembly or Delphi)
  2. Instantly create some mini native utility, or create some adhoc report for my user.
  3. Fine text editor
Sake
+10  A: 

The Portable Apps website has a load of applications that may be useful, such as WinMerge, Notepad++ and Gimp.

If you do a lot of web development that I believe thatAptana will fit on a thumb drive.

Sean
+16  A: 

I use a 16GB USB-Stick (larger volumes are available) as a Linux-system, that contains my complete work-environment. Every computer I use boot from this drive into my system.

Mnementh
May I know which distribution do you use ?
Sake
Ubuntu 9.04. This detects the correct screen-resolution on different machines.
Mnementh
I'd absolutely follow your path. I've found some guide to do this via google. Any tip you can share ? Would it be fine if I'll try Kubuntu instead ?
Sake
This is a great idea! Thanks for sharing that.
Jon Ownbey
@Sake: As far as I know Kubuntu only differs in the default Desktop-environment, that should be fine. But I don't know if Ubuntu 8.10 works. Other Linux-distributions should also work, try it out :-)
Mnementh
Ubuntu can install itself onto a flash drive and make it bootable. Just boot the LiveCD and run the "install onto USB drive" app.You can also look into Wubi for doing a similar install.
Barry Brown
@Barry Brown: As far as I know this only creates a live-CD on an USB-stick. I did the normal install on the stick, it works fine if you have enough space.
Mnementh
+2  A: 

and FTP program like WinFTP and crossloop

northpole
+11  A: 

I recommend .NET Reflector

Thomas Levesque
A: 

If you are carrying around sensitive data, I would recommend an encryption tool like Toucan.

Other great portable apps can be found at portableapps.com.

jinsungy
www.truecrypt.org is also a good encryption tool and is open/multi OS
kruczkowski
+3  A: 
Conrad
+3  A: 

I use to take with me UnixUtils.

UnixUtils are a set of commands of Unix ported to windows, so I only have to add a directory to the windows path and then i'm able to use most of the common linux command in the shell of a windows machine, making my job easier.

Jonathan
This looks nice, I'l have to try on my win machine sometime soon
LuRsT
A: 

Gvim

LuRsT
A: 

I would have to second Sean's recommendation for PortableApps, since it sounds from your example like you might be doing pc troubleshooting and not development work. PortableApps provides portable versions of a number of significant tools you might need that will run completely from a thumb drive, including Firefox (browser), Thunderbird (email), FileZilla (ftp), and Open Office (word processing, spreadsheet, database, etc.), 7-Zip (zip file management), etc. If you happen to be a .NET developer troubleshooting an application problem, you might want to check out SharpDevelop which will run completely from a thumb drive.

Rich
Rich, the example is just an example to get people thinking. I tend to do development work and client-side debugging off of a thumb drive at times.
Rob
+1  A: 

As a WPF/Silverlight developer I would add Kaxaml and MS Blend

Gordon Mackie JoanMiro
+3  A: 

I would add LINQPad to this list. If you have to do anything at all with LINQ queries, it's must-have software. It has a self-contained executable so you could run it completely from a thumb drive if you wanted to.

Scott A. Lawrence
+1 for LINQPad ! And it's not restricted to Linq, it's also very useful for quickly testing a piece of code without creating a VS project
Thomas Levesque
+5  A: 

I have a lot on one of my keys, mostly asm related.

I also have

And some other stuff that I can't remember as I don't have it on me :'(

I also have a usb key with backtrack3 on it and one with a windows image that I can use to install it on my netbook really quickly. I think this is a good guide on doing that.

PintSizedCat
+1  A: 
Josip
A: 

Everything mentioned thus far is great.

However, if you're like me and tons of folks are asking you to deliver demons from their PC because they're not savvy users, then you'll also want to have a copy of a free virus protection software like AVG.

Boydski
A: 

Expresso is a must-have for designing and testing regular expressions

Thomas Levesque
+5  A: 
Dale Halliwell
A: 

I have ubuntu linux installed to my usb flash with: GIMP Eclipse NetBeans

SomeUser
A: 

I have a 160 GB portable hard drive from Western Digital -- So I carry around a lot of stuff with me.

In no particular order:

  • XAMPP
  • Portable Python

  • 7-Zip

  • SysInternals Suite
  • DOSBox
  • PuTTY & PSFTP

  • MySQL GUI Tools

  • Notepad++
  • RegexBuddy 3
  • LINQPad

The installers for every major web browser, Komodo Edit, Cygwin, Git, and my favorite Python modules.

Sean Vieira
A: 

I keep my acme-sac (inferno-based vm) builds for all platforms I interact with - Win, Mac, Linux, BSD. That way I always have my preferred work environment with me. For Win, I also throw in cdb.exe so I can have a real debugger instead of that DevStudio monster.

Paul Lalonde