Seconded. There are a few hackerspaces [1] there. The Chaos Computer Congress is great. If you're thinking of moving there, knowing German makes things easier, but you can definitely get by without it. The nightlife is definitely one of the best in Europe. As the comment above said it's very cheap. I'm seriously considering moving there once I have a bit of money saved so I can work on my own projects for a few months without burning through cash too quickly.

[1] http://hackerspaces.org/wiki/Hacker_Spaces