If you're a Java coder, by now you've certainly wished something like this: "I wish Java had this of Ruby.. I wish it had that of Python.. that of Smalltalk" and similar. I came across the Groovy language just a few days ago and I started to enjoy its features immediately. It brings together the best features of the 3 mentioned languages: Ruby, Python and Smalltalk; all of that built upon Java and its greatness :) Well, frankly I can't say "the best" features, since I'm not into any of the 3 languages, so I don't really know what their the best ones are. But I know, that it is the great things like closures, convenient list and map notations, optional dynamic types and others, that are still missing in Java and it's unclear whether we'll see any of that implemented in Java itself any time soon.
Have you not already done so, let me recommend you to check out the official Groovy web site and go through the brief lists of the language's features. If you do, I bet you will soon find some spare time to dig a little deeper and check it out with your hand on it.