Photoshop Disaster is a new blog dedicated to finding (and making fun of) bad photoshoppery in print media, ads, and product packagings. They've got a lot of examples, some quite famous (like the belly button-less Brazilian Playboy model [SFW]), but a lot I've never seen before (like the mutant Lady Guineviere's third hand in Castle in the Air novel)
This one above is a Spanish newspaper's attempt in covering up a rival newspaper's ad by replacing it with ... clones!