i know its been a while but here are some more specific areas:
Bergmannstrasse in kreuzberg for all kinds of stuff, Kollwitzplatz and surroundings in prenzauer berg for nice little restaurants and bars. Of course, if you prefer something a little bit on the posh side, mitte is always good. especially around hackescher markt. And even more specific: if you want to have a drink in the sun (if there is any) in a somewhat strange bar (transformed coal shop) then go to prenzlauer berg (U2 till schoenhauser allee) then turn west (but south of the railway) till you hit the sonnenburger strasse. at the northern end there's the "Kohlenquelle". As i said, always good for some booze in the sun that one, although a little bit strange with all those east-type grey houses around and the flea market furniture. have fun