Scala
Scala is IMHO the best programming language we have seen so far.
In the future, I'd like to write here why and post some cool stuff you can do with Scala. For the moment, let me just give you the following links:
- The official Scala website
- Scala documentation
- How to install Scala on Ubuntu/Debian
- simplyscala.com, an online Scala read-eval-print-loop and tutorial. Try Scala without installing anything!