Hangover 3. Reviews were pretty rough, but I thought it was very funny and a good end to the trilogy. I thought Hangover 2 was just the original, in Bangkok, and was not a fan overall. I liked the focus on Chow.
Kingdom of Heaven (2005). I really liked this movie. It was like the 9th major swords and sandels epic over a 5 year span, and there was definitely some audience fatigue on the genre when it came out. I am not a huge fan of Orlando Bloom or Eva Green for that matter, but otherwise the cast was pretty strong, especially Ghassan Massoud as Saladin. I have heard that the Director's cut is even better than the regular movie, but I have not seen it.
Smoking Aces. A bunch of cartoonish assassins go to Reno to kill Jeremy Piven, who is basically playing Ari Gold. This movie is just a fun film to watch. The plot is ridiculous, but it doesn't really matter. Enjoy the dialogue and the shootouts.
Boiler Room - Giovanni Ribisi is amazing in this movie about a Long Island bucket shop, stock brokerage. I am sure people walked out of this movie in 2000 wondering when Vin Diesel would win his first Oscar.
25th Hour - I am not sure how underrated this movie is, because it got a lot of love when it came out. Still, it is probably Spike Lee's best film.
Tin Cup - There are a lot of places this movie could have gone wrong, from its slow pacing, to a cast with inconsistent Kevin Costner, mediocre Rene Russo, and weak Don Johnson, to the fact that it is a movie about golf from the 90's without a Tiger Woods cameo. This is one of the funniest sports movies ever made.