The Crea Café is part of the Universiteit van Amsterdam. Until last year it was located in between Spui and Waterlooplein. Nowadays you can find it inside (but still on the outside) of one of the main buildings of the university near Weesperplein.
Crea does a lot more than serving beers and snacks, but that is not relevant for travelers. If you want to meet local students in their natural habitat and offer them a cold beer in trade for some good stories, this is your place.
Beers are always €1,50.