The full list can be found here, but it's an odd assortment of films, to say the least. Also, just to put a personal touch on this, these are the ones from the list that I hold near and dear to my heart (and again, drop by EW's site or follow that link above to see all 25):
Dazed and Confused
This is Spinal Tap
The Shawshank Redemption
-What are your essential cult movies?