Scala

I've been spending a bit of my spare time learning Scala. I like it because:

1. It compiles to Java bytecode
2. It can use any of the Java API's - the years of investment I have in them translates seamlessly to Scala development and I'm productive almost immediately
3. Functions are first class citizens of the language allowing for higher order functions leading to a more expressive language

It has a some other benefits, but I haven't fully learned the language just yet, so it's hard to say I like it because of things I haven't experienced.

The main drawback at the moment is lack of IDE support. I'm using the scala eclipse plugin, but it is primitive compared to the Java support I'm used to in eclipse.