First link is a good essay on Bombadil.
Second, if anyone isn't familiar with "The Encyclopedia of Arda",
a great page with massive ammounts of information, then there it is. The link is to the Bombadil entry, but the main page is the third link.

http://www.cas.unt.edu/~hargrove/bombadil.html
http://www.glyphweb.com/arda/t/tombombadil.html
http://www.glyphweb.com/arda/default.htm

Most information on Bombadil is there. On a sidenote, Bombadil was/is being removed from the movie (movies?). Bad choice in my opinion. I feel that Bombadil was a needed character, which shows that however powerful and world altering the rings and their surrounding struggles, everything was not touched.