We don't see many hand painted posters for movies these days. All of the posters for the Disney animated films used to be hand painted with airbrush, it's a dead art form when it comes to the movie marketing machine now. These days everything is terribly photoshopped.
Director Brad Bird revealed a great hand painted poster for The Incredibles by Robert McGinnis. This is my favorite Pixar movie, and this poster is so much cooler than anything else that was released for it.