Sorry if repost, but I saw this on another board, and thought it was cool.
http://www.theyshootpictures.com/gf1000.htm
This is as definitive of a list of the greatest movies of all time as I've ever found.
"The January 2010 list of the 1,000 Greatest Films of all-time has primarily been compiled by using 2,041 individual critics' and filmmakers' personal lists/ballots of their favourite/best films."
Lists of favorite movies are taken from filmmakers and critics and combined to form this ranking of 1000 top films.
"Narrowed down from a starting list of over 8,800 films, utilizing some rather tricky formulas, we believe that this is quite possibly the most definitive guide to the most-acclaimed movies of all-time. At the very least, it is a rather spiffy place for all budding/established film buffs to commence/enhance their cinematic experiences."