I just came across this little item. Thought it may be of some use (or entertainment) for someone...
              http://virtualguitar.net/live/Strum.php

Hey, thats a nice little tool. Would be cool if it would actually name the chords that you build, not just the notes. It would be more useful then, but its still a nice tool.

I've always been pretty impressed by this little tool (which may be more what you're looking for Puppet), it includes pre-defined chords, however, is almost a half-MB download, so a bit larger in size:

http://www.chordbook.com/guitarchords.php

If you're on a mac, and want to learn Piano Theory, I've put together a nice little widget for your Dashboard... I'm not sure whether there is anything like it for the web on the PC quite yet... maybe sometime when I've got some free time I'll whip something together:

http://www.apple.com/downloads/dashboard/music/pianotheory.html

oh yeah, I really like the first link you posted there, Mud. That seem like it could be pretty useful. I have only a pc so I couldn't make use of the second...

yeah, that chordbook is great! THAT'S the stuff alright. Can't use the second link either, ..