We've featured graffiti on the blog before, but I just found a great post on a graffiti forum. It's a list of the top 35 graffiti pieces for 2007.
Art by Banksy, Blu, Sqon, and a host of others is presented in large photos. There's a lot more content on the forum, including a column specifically devoted to the best graffiti ever.
If you like graffiti, you'll love this site.
Graffiti moss on Whidbey Island.