there are several around houston
here is a thread about one building covered in them
http://www.texasphotoforum.com/forum...ad.php?t=61505
and marco usually posts some great graffiti shots a few times a month
here is one of his threads
http://www.texasphotoforum.com/forum...ad.php?t=59616
look at threads started by him and you'll see a lot of graf shots. Might be a drive for you, and some of them may have already been covered up. Maybe we should have a meet up for people to get some shots of graffiti

Also since you live in crosby, every now and then you will see some on the sides of the beams sitting on new 90 right at the beltway, but they usually clean those up pretty quick and I probably wouldn't risk going up there.