Slither - I'm not a fan of gross-out movies, so a film featuring slugs and mutants did not interest me in the slightest. It turned out to be a very enjoyable film.
Super Troopers - Like many, I was expecting this to be brain-dead comedy that only stoned idiots could be convinced to enjoy, but it turned out to be one of the best comedies of the year and has great repeat value.
Not Another Teen Movie - I normally hate these genre parody films, and I didn't want to like NATM, but I actually laughed a lot, in spite of myself. The cast full of hotties helped.
Bring It On - I only saw this after the firm assurance from a trusted friend that it was actually pretty good, and he was right. The tone is completely ironic, and it has some great lines, such as, "Cheerleaders are dancers who have gone retarded. What you do is a tiny, pathetic subset of dancing. I will attempt to turn your robotic routines into poetry, written with the human body. Follow me, or perish, sweater monkeys."
Charlie's Angels - I'm not generally a fan of the "waifs beat people up" genre. And to be fair, the weakest link is the Angels themselves, but around them is a nice candy-coating of solid supporting actors including Bill Murray, Sam Rockwell, Crispin Glover, and Tim Curry. And yeah, one or two of the action sequences are solid.