Through the power of a Twitter search column in Tweetdeck, I found a great InfoQ article which did a quick summary with lots of links to what's new for Java 7.
After reading through this, here are some of my favorites:
Automatic Resource Management
Tired of closing input streams, SQL connections, sockets, and so on? You will no longer need to in Java 7. Sweet!
Generic Type Inference
Allows you to leave off specifying generic types if they can be easily inferred.
I'd show you an example but this stupid Blogger editor gets completely confused with all the less-than and greater-than symbols, and I simply don't have the time to futz with it.
Closures through Lambda Expressions
This looks like a very promising implementation of closures in Java. Of course the devil is in the details, but I look forward to making use of this - personally I'm quite tired of anonymous inner classes.
Modules (Project Jigsaw)
I have worked with NetBeans modules and played around with OSGi, and I have seen the power of a well-defined module framework. I look forward to seeing this as part of the language (again, hoping it is implemented well. We'll see of course).