This is a new one, but a great one - The Cabin in the Woods. This film takes the traditional "college kids at a creepy cabin" theme and throws some wrenches into the works. It's got a lot of quotable dialogue and pop culture references and gives a refreshing new perspective on a fairly overworked plot type. Be warned, there is gore and blood and more gore and surprising deaths that may (in my case, will) evoke shocked laughter. If you're a Joss Whedon fan you'll be happy to know that he is one of the writers, and it shows.