Banned Books Week is 29 September through 6 October, and Google Book Search has put up a nice page listing some of the banned books with links to search for them with Google Book Search. Unfortunately, it's not quite as useful as it might be.
A number of these books are freely-available, public domain books (for instance: The Call of the Wild by Jack London; The Jungle by Upton Sinclair; Ulysses by James Joyce) and part of what makes Google Book Search really useful is that (in addition to searching through snippets of many books) you can read public domain books online. The banned books page on Google Book Search makes no mention of which books have editions available for online reading, which is really a shame.
This aside, though, I am glad that google is putting up a page for this at all; the positively obscene number of challenges that many of these classic books get is something that ought to be better-known to all. It's frightening how many great books people want to remove from our schools and libraries in order to 'protect the children' from 'dangerous thoughts'.
Of course, the proper way to celebrate Banned Books Week is to actually read a banned book. I remember that The Jungle was discussed in a modern history class I once took, and it is available online (and I imagine at my university library as well), so I may try to read it in the coming weeks. It'd be a little late as a celebration, but still probably worthwhile. I'd encourage everyone to do the same.