http://roguesurvivor.blogspot.com/

Turn-based roguelike zombie survival game, still in alpha but good for burning an hour or so.

You level up at dawn every morning, not based off XP or anything, so survival is more important than kills. Best bet is to bolt through the neighbourhood grabbing up groceries and maybe a hand weapon, find a nice little bolthole, close (C) the doors and windows, smash up (K) some furniture, barricade (B) the points of entry, then sleep (Z) and wait (W) until you run out of food. Rinse and repeat. If you take a few hits while doing so, you can heal quickly with medkits and bandages or slowly by sleeping on a bed instead of the floor.

Best I've gotten so far is lasting a fortnight with a kill-count hovering around 200 or so.