The authors of I Hate People, Jonathan and Marc, customized their rental car so it was a rolling advertisement for their book. A brilliant move I think,  although perhaps a bit dangerous in New York City. Check out their post, which also describes the excitement they generated  handing out promotional swag in Times Square.  These guys are getting piles of attention in the main stream media, CNN,Wall Street Journal, and New York Times. So I have to hand it to them because they are doing the guerrilla marketing thing too.