photo from i core (found via TinyMeat)
Graffiti artist, Scott Wade, uses ordinary artist brushes to draw on the back of dusty car windows. He lives near a dirt road covered in caliche - a mixture of limestone dust, gravel and clay - which, when driven over covers the car in a fine, white dust.
I don't know about you, but whenever my windows got dirty, the only thing that I ever drew were hearts and maybe the occasional 'hi' and 'hello'.
You can see more of his work here.