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?
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.)