This semester (Fall '05) I'm one of the teaching assistants for Calculus in 3 Dimensions, 21-259. Useful information on homework, test dates, grading and the like is on the main course webpage. I hold office hours for students in my sections (B & I) each week Monday 4-5, Tuesday 11-12, and Thursday 11:30-12:30.
My shared office is a little difficult to find: it's in the Physical Plant Building (aka the PPB, officially the Facilities Management Services Building), which is between Wean and Hamburg Halls, down behind Newell-Simon; it's the building with all the ostentatious heating/ventilation machinery sitting on top of it. It's number 17 on the official campus map, but kind of hard to see on there.
To get to the PPB from Wean Hall, take the elevator down to the 1st floor, follow the corridor around to go out of the main door there, cross the road and turn left on a little path. Follow the path around a corner until it opens out into a tiled area with some picnic tables, and then follow allong by the wall on your left until you come to double glass doors; go inside and carry straight on into my office. Alternatively, if you're coming in from Forbes on the driveway between Hamburg Hall and the CIC (the last one before the bridge over the railway), just go straight ahead and down some stairs to get to the aforementioned tiled area with picnic tables; the glass double doors are then diagonally ahead of you and to your right.