Also, can't say I've ever used any of these, but a quick search resulted in...
chordfind.com
chordbook.com
looknohands/chordhouse.com
guitarchordsmagic.com
gravityboy.com
users.netrover.com (requires Java)
wikipedia.com (article about chords with another extensive link list at bottom)

And there's many more, but that's what came up first. Mel Bay is my usual reference though.