I found this article about a mosaic mural in Philly that just keeps growing (and no, it's not the famous one by that crazy guy on South Street). It's in North Philly and the community keeps adding to it. Check out the pictures, they're cool.
I went around by the University of Texas, and it was a pretty hip art scene. The frog mural ("Jeremiah") is apparently very famous, done by a local musician. I found a few articles about it, this one I thought was the most interesting http://www.rollingstone.com/artists/danieljohnston/articles/story/5935521/johnston_frog_mural_saved
The rest are just some pictures from around the city.