To me, Cafe Europa is less of a destination than a fallback: It's the place to go for a bite after midnight (that isn't McDonald's), and the place we always seem to end up at when we can think of nothing else. Decent size, pleasant atmosphere, good tunafish Ciabatta.
This has got to be one of the most comfortable, laid-back places in town. The food's delicious if you appreciate mediterranean cuisine. They also have power outlets, Macs for rent, and free wifi -- so you can get some work done here, too. The only thing disappointing about the Ronahi is their website.
Plenty of space, a great atmosphere and free wifi make this an awesome place to get some work done in the afternoon or just hang out with friends later in the evening.
Think Phil or Möbel, but with superb and cheap food (limited to 2-3 new and unique choices each day). They also host interesting cultural events from time to time.