Check out libraries, bookstores or online retailers for these fun looks through the history of movie posters (the McHenry Museum gift shop even has some of the titles):
"Film Posters of the 90s: The Essential Movies of the Decade," by Tony Nourmand and Graham Marsh; the authors have books for each decade back to the 1930s
"Reel Art: Great Posters From The Golden Age Of The Silver Screen," by Richard Allen and Stephen Rebello
"Trash: The Graphic Genius of Xploitation Movie Posters,"
by Jacques Boyreau
"Attack of the 'B' Movie Posters," by Bruce Hershenson
and Richard Allen
"The Star Wars Poster Book," by Stephen J. Sansweet
and Peter Vilmur
"A Century of Movie Posters: From Silent to Art House,"
by Emily King