Where to find special German beers?

What can be more special than coming to Berlin and drinking a nice cold beer?. Well in Berlin you can find in almost every corner a "späti" (small store which opens sometimes 24 hours)  where you can different options.

If you are more interested in bars. There is a Bar in Mitte, called Aufsturz, where they serve more than 100 different beers (not too expensive): http://aufsturz.de/

There is another placed called Eschenbräu, a small brewery with many but many beers. But I can not say a lot about it since I have never been there. :-)