Cult movies

The Big Lebowski -- Best. Cult. Movie. Ever.

A Clockwork Orange is freakin' amazing. One of my favs. Donnie Darko, the directors cut espically, will blow your mind. I can't believe no one has mentioned Akira yet, that is one of the greatest movies of all time. period. also, Ghost in the Shell

Christ I hate the term cult film I never know what it means.
But I think what falls in to that catagory or there abouts is:

Dogma - One of the best films I have ever seen.
Fight Club - I think it helped me appreiciate the opposite sex a bit more.
Amelie (I am not sure if that counts) - It's like a big warm blanket.
Run Lola Run - I find this film hypnotic I am not even sure why I like it so much.

A "cult" fim is basically a movie that wasn't popular and didn't do well at the box office, but later developed a cult-like following.

Thunder in Carolina: a great early 60's racin movie with Rory Calhoun in the lead role.
About the fast lives of racers in NASCAR infancy.
Also
Wild Angels: 60's biker movie with Peter Fonda and Nancy Sinatra. Also starring Bruce Dern as The Loser.