Terry Posters is an amazing online database with over 6,000 film posters from all over the world. You can search by designer, film origin, date, film title, director, actors and more. It's a little hard to find your way around at first, but well worth the time. Mostly featured are vintage posters and some posters are even available for sale, but there is also a section of contemporary posters. There is just so much great stuff in there.
Link found at Montague Projects Blog