Which do people like more? Seeing the movie first and then reading the book or vice versa?

Think how many parts of the Bible have been made into movies? That's probably the most filmed book in the Western Hemisphere.

Other book/movie combinations to recall and/or look forward to:

One Flew Over The Cuckoo's Nest
MASH
Gone with the Wind
The Wizard of Oz
Ben-Hur
Catch 22
Lawrence of Arabia
Doctor Zhivago
War and Peace
Mystic River
No Country for Old Men
Reservation Road
The Godfather
Band of Brothers

What other movie/book combinations can people recall? I remember that at the Palm Harbor Library there was a woman volunteer whose son wrote or had something to do with the Road to Perdition book which was made into a movie with Tom Hanks.