Have you heard of yarn bombing? It's a kind of "street art," like graffiti, only with yarn rather than spray paint. Essentially, it involves creating legwarmers or sweaters for street signs, parking meters, and mailboxes. Even bridges and buses have been bombed. The New York Times described yarn bombing "tak[ing] that most matronly craft (knitting) and that most maternal of gestures (wrapping something cold in a warm blanket) and transfer[ing] it to the concrete and steel wilds of the urban streetscape."
All yarn bombing I've seen in person has been small scale--I've never seen anything quite as extravagant as in the pictures below in person, but I think the concept is really cool.
(All pictures courtesy of Yarn Bombing.)