In addition to the one in the first response, here's another one with explanations:
http://www.h3.dion.ne.jp/~urutora/buson.htm
Explanations are in Japanese :)
If you're having trouble reading them because of kanji(which is normal), try googleing rikaichan/rikaikun depending on whether you use firefox or chrome. If you're using something else, I'm not sure if there is a similar add-on.