I don't know where to stick this one - maybe "alternative" category... but I have to include "Magnolia" just because Tom Cruise plays one of the coolest characters (sex infomercial/inspirational speaker) ever.
DRAMA - hard to top Godfather 1 and 2
COMEDY - a tough one...Bill Murray theme: Stripes, Ghostbusters, What about Bob, even Meatballs, Ground Hog Day...he's the best. Honourable mention to Me , myself and Irene
ACTION - have to concur on The Matrix
80'S - Diehard and Raiders of the Lost Ark were memorable experiences in the theater..guilty pleasure : Ghostbusters
unknown: Hollywood Shuffle
WICKED MOVIE - Pulp Fiction
new category - WAR MOVIE - Platoon
BEST OLDTIMER / MOVIE OF A BOOK READ IN HIGH SCHOOL - To Kill a Mockingbird
Though I don't want to suggest it's by any means The Best War Movie, I recently rented We Were Soldiers. It's not half bad -- a bit rah-rah-America, but not too bad.
All-time though? The Bridge Over the River Kwai and Tora, Tora, Tora. They don't make 'em like they used to.