I watched several this summer, quite a few on video/DVD, but many in the theater. A couple of my favorites so far are...
Next (cool concept and a tricky ending),
Transformers (awesome special effects, though they could have developed the characters a bit more; i.e., too rushed),
Bridge to Terabithia (I know, kids movie but I still enjoyed it quite a bit and so did my wife),
The Number 23 (cool mystery/suspense thriller, though a little predictable),
Conversations with God (hey, I liked the books so I had to check out the movie, which was pretty darn good).
The Banquet (Chinese film with a lot of cool action and nice cinematography), and
The Fountain (had to watch it twice to really see what was going on, really enjoyed this movie too).
I've actually seen a ton of other movies too, but these are the most memorable in my opinion (saw quite a few stinkers too... man, I wish I could have those hours back!). Good luck picking movies to watch, I'm sure you'll find someone here who shares your taste in film since I know we all have different tastes.