Borst's "Graven Images" will keep you collecting forever.
Any of the Stan Choko books on french posters, I'm particularly fond of "100 ans d affiches de cinema".
"Film Posters of the Russian Avant Garde" by Susan Pack is truly mouthwatering for those with an interest in such things.
Oh, gotta throw in Gresham's "Children of the Night," while not up to "GI", it's an invalualbe resources for UniHo material.
--Peter