Here's another graff app I ran into while @ 000000book.com
Graffiti Analysis (iPhone) - DustTag v1.0 from Evan Roth on Vimeo.
The app is truly revolutionary. I still haven't figured out how to use it to it's potential, but as you can see in the video, it's pretty amazing! It only costs $1.99 so it's worth checking out. It's a cool idea...but I think it needs some tweaking. Read more about it here.