A few nice airbrush tutorials images I found:

Serbian Graffiti self portrait

Image by thesqueedler
Inspired by the kind of graffiti in downtown Valjevo, this is the result of following the "Create a Dark And Surreal Poster Using Your Own Portrait on PSDTuts. Maybe a little egotistical but I don’t care 🙂 Amazing what you can do with even a little bit of airbrushing. Does it even look like me?

See psd.tutsplus.com/tutorials/tutorials-effects/create-a-dar… for the tutorial.