Punting on the River Cam is de rigeur if you're in Cambridge for the weekend, and the punting pubs lining the river are the mutt's nuts as well. Cambridge is a superb location if you're looking for an activity weekend, stag party away from the hassles of bigger cities. The clubbing is not as varied as in other places but there are still plenty of places where you can build up a good head of steam and there are loads of more modern style bars away from the river.
You'll also be spoiled for choice when it comes to choosing actyivities for the daytime.
Apart from the punting there are the usual stag do options like karting, clay shooting and paintball but also more unusual options. Falconry followed by rallying, anyone?