I watched Timecrimes on Netflix streaming video. It was excellent. It met many of my criteria for a good time travel movie: It had a time machine and they used it several times, there was a time loop and the protagonistic had to work hard to eliminate and prevent any paradoxes.

The middle of the movie was really slow but presented a lot of details which were critical to the ending.

The movie is in Spanish, looks like there will be a new English version in 2011.