Personally, I would either go out for a few hours and play pool or watch a movie with friends or play some games on my PC. They just take my mind off exams and what not.
I did run 3 times a week which actually relieves stress but i don't have the time for it anymore because of other commitments.
Honestly, anything you enjoy. It could be reading, walking, watching Youtube videos, drawing, listening to music, dancing anything!