most of the ideas posted are things i thought would be great already, about the time of harvey dent sites i thought putting up signs then later having people deface them would be awesome.
also someone said superbowl, an ad "interuprtion" would be great but it should tie into a joker website, with ofcourse some prizes ($) to attract people watching, and it should occur during halftime only, it would be neat i think, see how many people ditch the always...amazing....halftime show to go try to win on a joker website.
also I think that joker should appear at public events, risky yes, but still. he could throw around fake money like why so serious. it would make national news. imagine if this week with all the micheal vick news and stuff a joker man shows up and does something. instant free publicity, pay some guy to run around and do joker-esque stuff. ofcourse they would have to chose properly to do this. (mike vick would be fine, its already a crazy show out there, I know i live a few blocks from where they had his hearing).
they could also have college students joker-ize their schools with his writing and setup vandalization.
pretty much i think the viral marketing should get up to the level of almost causing problems, people thinking there is a gand of vandals leaving his mark around towns.