The People For The Ethical Treatment Of Animals has released a list of 10 movies they claim will make you go meatless. A sample:
Babe (1995): This film has turned legions of people into vegetarians–including its star, James Cromwell–because who could "pig out" again after watching that cute little piglet charm Farmer Hogett?
Also included, I Am An Animal, a documentary about PETA founder Ingrid E. Newkirk (but of course), Delicatessen, The Texas Chainsaw Massacre, Soylent Green, and Sweeney Todd. (Those last few sound more like anti-cannibalism movies to me, but whatever.) PETA's site includes the full list.