Urban Graffiti

I don't know where my fascination with graffiti stems from, maybe it was growing up in a depressed urban area. I've seen a lot of it on the streets of Flint, Michigan. I find what people choose to say with a can of spray paint very interesting. The world is their canvas. This site, www.picturesofwalls.com, contains 4 galleries of photos depicting graffiti on walls and objects that were taken in cities around the world.
Interestingly enough, there are reoccurring themes; my favorite are the obligatory anti-government and anti-commercialism ones. It seems graffiti artists are just saying what we all wish we could say but don't want to risk vandalism charges to do so.