One of my favourites is the bait-and-switch. Back when I had a gallery here, the thumbnail showed a semi-naked woman in shadow viewed through venetian blinds. You click on it, and the main image is her very angry father, threatening you with serious bodily harm if you look at his daughter again. That one got more hits in a 24 hour period than anything else I'd ever done.

docandraider.com -- the collected cartoons of Doc and Raider