I've never been happy with anything I've ever found. But not having good UML, or at a minimum some clear class diagrams, makes it difficult to move forward with design on a team. Especially if you're a team deeply engrained in Agile concepts wrapped in Scrum.
UML Tools? Visio? Visual Studio? Other?
UModel by Altova Software is my UML modeling tool of choice. Other people will still use Visio just for the availability and familiarity. Another big and popular tool which will probably do more than most people ever really need is Rational Rose.
Personally, I really like using Microsoft Visio and the following UML 2.2 template (http://softwarestencils.com/uml/index.html)
This gives me the freedom to draw whatever I want, where I can decide myself if I really want to follow full UML syntax, or have a bit more freedom if that makes a model easier to understand.
Whiteboards and digital cameras.
If we need something more maintainable, I like SmartDraw. It's a lot easier to use (and prettier) than Visio.
Check Balsamiq Mockups and the myriad of cloners. Great help at least for the UI designing part.
And of course, check paper prototyping! (seriously)
I like Visio, but Dia will do in a pinch. Typically, I put together high-level architecture diagrams and then class diagrams, have them peer reviewed, and then use them as a reference while I implement from the bottom up using TDD. I find that this tends to result in loosely coupled code and systems, and pretty good adherence to the YAGNI principle.
Microsoft Visio (UML) and Balsamiq Mockups for UI Wireframes.
I use BOUML. It's opensource, round-trip (sort-of), and can do multiple languages including C++, Java, PHP, and Python. It's also very fast and robust. I use it under both Windows and Linux.
There are many parts to a conceptual design. Depending on which part you focus on a variety of tools are out there.
As with most computer things, Capturing it is easy, filing it away so you can find it later is critical. You won't use all of these tools 100% of the time, but they all need to flow to one central spot.
For me that is Fogbugz because it's simple, works, has a wiki and forum built in and I can do some basic workflow management.
Building a system that files things at the point of capture without having to process it many times (create it, then process it, and then file it so you can find it later) will save you a ton of time.
CREATE:
Tabloid size graphing paper (never run out of space)
Balsamiq Mockups with xwiki (keep your mockups evolving and tracked easily in the wiki with each revision)
OmniGraffle / Visio (Flowcharts, graphs, etc.)
Whiteboard. I have one big whiteboard right now. I'm getting ready to purchase the superb WallTalker product. It doubles as a projector screen, can come pre-printed with a grid on it like graphing paper, about $27/linear foot for a 60" roll. $300 for 13' feet of writing space!
CAPTURE:
Fogbugz for tracking as much as I can. The key part is being able to email myself anything and everything. Free hosted editions for 2 users online. Integrates directly with Apache Subversion, etc.
Phone camera for whiteboard I use my cell phone and send it straight as an email into Fogbugz, making sure to put some notes in the subject and email of what it's about so I can find or link it together later. I know regular cameras take better photos, but do we really sync our cameras more, or our phones? I've had good success with an iPhone and my current HTC.
Skitch - Excellent for taking a screenshot and doodling on it. Can be done with images, screen renders, etc. Especially helpful when sending clients a screen to point out certain things. A comparable windows product would be Snag-It, etc.
Email everything - email yourself everything to Fogbugz. From your phone, from your software, from your servers, from your friends with ideas.
Fax - get a fax to email setup and send all faxes to Fogbugz. Aren't near a scanner, fax it to yourself, throw away the paper. You'll find it later if you really need it, and if not, you aren't letting paper distract you. When someone wants to send you paper, if there's no PDF file, voila.
ARCHIVING:
I'm using Enterprise Architect by Sparx Systems at work. It works fairly well for UML modeling and can round trip to stay in sync with the code/generate the code. It also will let you generate documents (RTF), but I haven't played with that very much.
Something that I like about it over Visio is that in Visio it was just a drawing. In EA you have an object that you define the relationships to/from, that object may appear in multiple diagrams.
However my one complaint is that the software updates lag behind the code language changes, for example it's only in the last month or two that C# 3 has been supported, which caused problems when reverse/forward engineering with C# 3 code.
The universal tools: pen and napkins (with coffee stains, of course).
My brain.
This makes sense, since my coworkers tell me I'm one of the biggest tools ever.
I find a combination of Balsamiq mockups for user interface design and A3 paper for business logic and database design works for me.
Using a pencil and eraser means you can just edit your mistakes as you go along.
If it's been a while since you used UML it might also be a good idea to do a refresher.
The pencil add-on for Firefox is pretty good for simple diagrams and GUI sketches.
And if you don't like it as a Firefox add-on, you can download a standalone version for Linux or Windows.
Personally I use PowerDesigner, a really decent and intuitive UML diagramming tool.
One of the features I like the most is the ability to define a class in only one place and reference it in diagrams in another packages and even other kind of diagrams, like sequence diagrams. One change in the class (for example a method renamed) and all diagrams that use that class get automatically updated.
All objects and associations are fully customizable in case I need to do something "out of UML".
Visual Studio 2010 Ultimate supports UML class, sequence, component, use case, and activity diagrams. It also supports creating sequence, dependency graphs, and layer diagrams from code. Other tools include Architecture Explorer, which lets you browse and explore your solution.
For more info, see the following links:
To download the RC release, visit: Microsoft Visual Studio 2010 Ultimate RC
To see the RC documentation, see Modeling the Application.
To discuss these tools, visit the Visual Studio 2010 Architectural Discovery & Modeling Tools forum.
Give PlantUmlEditor a try. You can code diagrams at the speed of writing emails. No more struggling with designer environment and stencils. Draw diagrams as fast as you write emails.
according to microsoft we should use sketchflow
more info here on this blog
the main benefit is that you have xaml for markup and can edit that in expression and continue with silverlight/wcf stuff
here is a nice 5 minute video of it worth checking out!
Missing in this list is UMLCanvas http://umlcanvas.org - it is a browser-based solution that allows you to create and update UML diagrams with Firefox. Neat!