i think most uni's have two union-esque things
eg: UTS has got the Union, which does cheap food, a few newsagents and supply shops, funds the clubs and societies, that sort of thing. also, strangely, publishes a newsletter that is pretty much the voice of the Young Liberals club.
then there's the students association. that's got all those dirty, smelly, horrible activists in there. no, some of them are cool. others are sort of psychotic. but they're not all socialists -- in fact i hardly know any socialists in the SA. let's see: we've got anarchists, feminists, gay rights, greenies, education activists, refugee advocates, gay anarcho-feminist green education activists, that sort of thing. the SA do collectives (green, education, refugee, sexuality/queer, womens (or womyns), and probably more), organise rallies and demos, and other stuff like student rights, resolving staff/student disputes, etc. oh, and they publish vertigo, the uts student press. currently the SA is dominated by the broad left, but there's also some labor left in there too.