Some of these "guilty pleasures" movies named in this thread are considered to be classics; I don't know why you'd consider them guilty pleasures. I think the point was to name movies that in general are considered to be bad movies, yet you like them anyway.
Not exactly a guilty pleasure, but the BBC Pride & Prejudice probably doesn't net me any cred on this site, and I like it a lot. We have it for my wife, and I'm always bugging her to watch it with me. The pseudo-Bollywood version, Bride & Prejudice I also thought was lots of fun, and my wife didn't even like that one. I may actually buy a copy for myself!
Predator 2 and Alien vs. Predator are guilty pleasure movies for me, I suppose. I don't know why Predator 2 doesn't get more respect from the geek crowd though; I've always thought it was a pretty good movie.
And like glass, I have a funny thing for teenager chick flicks. 10 Things I Hate About You probably being my favorite of the bunch.