The Occupy movement has been going green, so why not make your green get Occupied? Occupy George has some pretty stark money-based infographics, and templates for printing them onto your own bills. Chances are any bill in your possession will eventually end up in the pocket of the 1 percent, so why not let it educate them while it's there?
(We checked, and this is legal — you're not allowed to deface a bill "with intent to render such item(s) unfit to be reissued," but these are clearly still circulable.)