Wow...tough question. I like someone's inclusion of Truman Show on this list because I thought it was a very interesting story line at the time and Carrey really surprised me in it....then he one-upped himself in one of the few love stories i like Eternal Sunshine.
As for me, there are quite a few I like for various reasons: Shawshank, Groundhog Day, Frailty, Fugitive, Godfather I-III, Unforgiven, Solaris, Master&Commander, Of Mice And Men, Prestige, Departed, Mr. Brooks, etc, etc
I also really liked Shutter Island, just saw it for the first time the other day. Ive read very mixed reviews though. Hacks.