Thanks to GeekTyrant, I found one of the more ... well-produced(?) trailer mash-ups I've seen in some time. It's footage of Disney and Pixar's film, WALL-E, with the soundtrack of the first Watchmen trailer, with some original graphics added in as well. Take a look:
This isn't the first Pixar/DC mash-up we've posted, actually. A few months ago I posted a quite humorous mash-up of Toy Story and The Dark Knight. Nice to see these things go hand in hand.