I really like Jon Klassen's illustrations - especially some of the concept art that he created for the movie, Coraline (I've yet to see the film, but really liked the book and love all things stop-motion). His work feels like a nice mix of Charley Harper and Alice & Martin Provensen, while still maintaining its own unique sense of humor. You can buy prints of some of his pieces, and even a couple of t-shirts he created, here.