Grendel's Den is a restaurant in addition to a bar, but the quality of the food ensures that most of its patrons come for the drinks and not the meals! The afternoon happy-hour special is decent, however, and as a nighttime hangout, Grendel's is a unique and cosy spot to try.
Walk down a small brick staircase and enter the brick and pine-paneled main room. Grendel's Den actually used to be a university-associated house, and the floor plan is unusual. This underground "den" has a main dining room, with two levels and a bar in the middle, and several more small tables behind a wall near the restrooms.
The crowd is definitely of the Abercrombie variety - mostly college-aged and all very happy and drunk, especially on the weekends. But drinks are relatively cheap and the bar tenders are friendly, especially if you tip well.