Best Movies:
The Godfather
American History X
Pulp Fiction
One Flew Over the Cuckoo's Nest
Se7en
(This is just off the top of my head, but I know there's better movies)
Worst:
Bio-Dome (or any Pauly Shore movie, except for Encino Man, and that's only because Brendan Fraser barely saved it)
Titanic (It's technically not bad, but for such an expensive movie.. it's pretty bad)
Pretty much any romantic comedy that is forgettable (If I remembered them, I'd list them)