Cafe Cine Express. It's at
1926 Ste-Catherine West. It's right before St-Marc, 3 short blocks from Atwater. It's close to Atwater and Guy subway stations if you're travelling like that.
The place is 24/7 and has a very relaxed atmosphere. In the front, you'll find very comfy couches and tables in front of fake fireplaces. In the back, they've got chairs and tables that double as backgammon or chess tables if that's your thing. Huge projection screen in the back as well that displays TV or student films. They've got a full menu actually, aside from coffee, and the place is very cheap. Free wi-fi too, I beleive.
I know I just wrote a novel about it; I just really like the place. I had many dates there as well as many late night study sessions when I was younger.