There's nothing more revigorating during the dark winter days than spending a couple of hours in a sauna. Germans have mastered the art of sauna and you can find amazing pieces of architecture in the public swimming pools (Stadtbad). I find Stadtbad Neukölln very peculiar in its neoclassic architecture and it's definitely a wallet-friendly option to enjoy some sauna time there. Be prepared to be naked in front of man and woman!
Best record store in Berlin. A great selection of Rock, Folk, Indie, Wave, Industrial and especially the huge floor dedicated to House and Techno Records. Staff are typical Berlin-Style - not very friendly but very knowledgeable.
It is an English language bookstore centering on non-western, diasporic, and queer perspectives.
Many many many rare and special books carefully selected by Siddhartha Lokanandi that is the soul of this place! Check it, it is unforgettable :)
A very close friend of mine owns this bar. It looks tiny from the outside, but it has two rooms you have to pass until you get to last one which is a discofloor. I play music there from time to time and I am always surrounded by nice people und friends.