I'd have one if it were a window sticker that you can move around... Not sure what they are made of/called, just like really smooth, shiny, thick plastic I think...and its usually clear plastic, that you usually put on the inside of your window, not the outside... And these ones you dont get that horrid gluey residue all over the place that is a pain in the *** to get off! More like a lick and stick suction type design?
Not a fan of bumperstickers... they wear out, fade and get really tattered and ugly really quick... I'd definately go one of those window stickers that you stick on the inside of your windows, not the outside... Much better and more practical IMO.