Soul Tree
Yet another Cambridge club with a 'formerly known as...' tag but thankfully no one really calls it Coco's anymore. The Soul Tree is a good place. There are three floors - the ground floor has a medium-sized dancefloor looked down on by the floor above through what is essentially a massive hole in the floor. Try not to get spat on. The top floor is the 'Penthouse' and is designed for more chilled out music when you need a rest from the frantic dancing. In general, Soul Tree is driven by chart R'n'B dance, and is EASILY the best club in Cambridge if that's the kind of stuff you're into: Fez goes too esoteric in it's dance music; Life compromises on the R'n'B with cheese, plays slightly more mainstream R'n'B, and gets the worst of both worlds; and Cindie's and Kambar REALLY aren't catering for that market.
Soul Tree is also a live music venue and has recently hosted acts from Kele from Bloc Party DJing to Johnny Foreigner. Its intimate feel and rudimentary barrier system makes this a very refreshing alternative for those who've only previously been to arena shows.
You can also rent it out, and there are frequent inter-college collaborations for events here, often run by Shut Up And Dance!, such as the annual "Better Late Than NYEver" party in which you celebrate New Year's Eve two weeks late.
There are, however, a disproportionate number of fights at Soul Tree, so do watch yourself.