Along the same lines as stencil art, but a bit different - Another cool thing I found recently on the web is http://thebubbleproject.com/ .. basically this guy made up these speech bubble stickers and pasted them on billboards and advertising, leaving them blank for passers by to fill in.. some of the things people have written on them are quite smart, like this one! " The exibit is over, why are we still here, Pablo?"