Daren Dochterman isn't just one of our favorite concept artists, who's worked on Iron Man 2. He's also the creator of these weird TV/movie parody posters. "Not Coming Soon" includes concepts like Dirty Harry Potter. "Do you feel magical, punk?"
Actually my favorite might be Co-Dependence Day, starring Meg Ryan and Tom Hanks. There's also a gruesomely funny scorched action figure for Uncle Owen and Aunt Beru, post-Stormtrooper attack.
For a few years, in various incarnations, I did humorous movie posters and bits for Eon Magazine online, and then CINESCAPE. It was brought back for a special edition of CFQ... and may come back someday. It started with my idea for a book of awful movie posters of "high concept" movies based on TV shows. When most of the movies came to pass, I abandoned the idea bitterly.
There are tons more hilarious posters over at the link. [Not Coming Soon at Daren Dochterman]