Donnie Darko has to be on my list, but I recommend you watch the original not the directors cut. The original has way better music and and it leaves you thinking more. DO NOT WATCH S.DARKO, boring.
Fight Club is still my all time favorite movie. Primal Fear is up there with Fight Club. Basically almost every movie that Edward Norton starred in is my favorite because he is an awesome actor, watch American History X and Primal fear and you will see what I mean.
Usual Suspects has to be up there because of the twist at the end.
If I were to keep on going this list would have like 50 movies so I will stop here.
Saw American History X yesterday
Fight Club = AWESOMENESS, I have it in 720p blurip, never gets old.