The "joke" question Joel asked during podcast #58 made me all nostalgic for Logo, which was the second language I ever programmed in, after Basic, and which is why I never had any trouble with recursion in college.
Are there any implementations of Logo for Windows or Linux (the platforms I can use) or Mac (because I know I'm not alone in this world)? How can I get the Logo programming language for my computer?
Cross-platform versions: http://www.mathcats.com/gallery/logodownloadinfo.html
MacOS X specific: http://www.alancsmith.co.uk/
Open-source Logo:
http://sourceforge.net/projects/fmslogo
http://www.rz.uni-augsburg.de/~micheler/en/
There is a pure-Python version of Logo available at http://pylogo.org/
UCBLogo is my favorite LOGO implementation, and happens to be available for Windows, UNIX (with X11 support for turtle drawing), and Mac OS X, with outdated ports for DOS and Mac OS 9 as well.
Most Linux distros already have it packaged.
It is also still maintained (thanks to cheap labor students at Berkeley), open-source, and very portable (I've run it on various flavors of UNIX, including Linux, and various processor architectures as well).
UCBLogo comes with a fairly comprehensive standard library and good documentation; the source code for the examples in Brian Harvey's "Computer Science Logo Style" books are also included.
Addendum:
papert - logo in your browser is surprisingly featureful, and seems to work in any modern browser.
To really recreate the nostalgia, you might try running Logo on an emulated Apple II. You can get images of Apple II disks for Logo here and the AppleWin emulator here.
I'm teaching my kids LOGO successfully on Windows using Elica LOGO. (Kids ages are presently 12 and 10.)
The package's strengths include many "advanced" extensions, beyond the basic 2-dimensional turtle. These include 3-D graphics and simple hooks into the Windows widget world. (You can create Windows forms with buttons, etc., from within your LOGO code.)
Lacks sound/music capability, at least in version 5.5, and the built-in documentation is extensive, with many advanced examples, but it's not very useful in my opinion--due to its incompleteness, and its having many coding examples that contain errors. (But my kids learn more by finding the errors in the programing samples.)
Here's a good free one for windows http://www.softronix.com/logo.html
And there's a parellel logo you might look at http://ccl.northwestern.edu/netlogo/
Also, MIT has a good parallel logo called starlogo http://education.mit.edu/starlogo/