It's rare that you find a really innovative film but Memento is definitely up there near the top. The plot is about a man, Lenny, who can't make new memories since the rape and murder of his wife. Lenny remembers everything before that event but his memory now only lasts five to ten minutes at a time. Lenny has only one purpose in life and that's to find his wife's killer and take revenge.
Christopher Nolan then uses this situation to explore lots of interesting questions about memory. How accurate is memory? How do you use memory? How can you remember to forget? How do you know what you want? Best of all, the entire narrative is from Lenny's perspective and in short segments that mimic Lenny's thinking. However, you start at the end of movie and you're shown progressively earlier and earlier segments of the movie until you get to the beginning where you finally figure out what's been going on. It's superb. Had to watch it twice to get my head around it.