Lexipedia is a neat visual thesaurus, and more. I think English Language Learners will find it helpful, and I’ve placed the link on my website under Thesaurus.
I’m not sure yet if I’ll add it to my The Best Reference Websites For English Language Learners — 2007 (you might want to check-out that list if you haven’t seen it already). I’ll need to “play around” with it a bit more to decide.
Let me know if you think I should put Lexipedia on the list….