I've recently come across two artists using Star Wars as inspiration for some unusual and very cool poster designs.
The first is the work of Justin Van Genderen, a graphic designer in Chicago. He's taken several key locales from the series and created these 1960's-style travel posters advertising them.
Interview at LA WEEKLY.
Artist's website here.
Then there's the work of comic book artist Cliff Chiang, who designed these three WWII-style Galactic Empire propaganda posters for a series of Star Wars trading cards.
Artist's Web Site