It's always surprising how many of the great movies came from wonderful books.

Those are some of my favorite:

Blade runner, which came from "do Androids dream of electric sheep" by 
Philip K. Dick

Lord of the rings (Tolkin)

Gone with the wind (
Margaret Mitchell)

Everything is Illuminated (Jonathan Safran Foer)

Perfume (I just saw the movie last week and it's great), the book is by Patrick Suskind

The Hours (Micheal Kunningham) - the movie is ased on a book which is a tribute to another book - Mrs. Dalloway by Virginia Woolf

Lord of the flies 

Damn - there are just too many!