(update: derp, we blogged this back in 2006.)
We've all seen smileys and "WASH ME!" on the dusty windows of cars that need a good cleaning. Artist Scott Wade takes that a step further, and draws beautiful, intricate art on dirty rear windows, including replicas of Vermeer, Michelangelo, and dogs playing poker. Lots more at Designboom, including photos and videos. Mr. Wade's website is, appropriately, dirtycarart.com.
(thanks, Joe Sabia!).