Ask YC: How to build a community online at a college?

I am currently attending a University that has no real online community, and I think this is a "bad thing." Universities are supposed to be about sharing of ideas, and collaborating and expanding your ideas with the help of others. I am curious how you all would go about trying to build a community online for my school. Presumably something close to a wiki/forum, but with a focus on education? Or should it be more of a free-form discussion, and try and get people to come out of pure chance. This is very similar to a startup, and building a community around one, but presumably the community is already there in some form, it just needs to be brought online. Anyone have any advice on how to go about achieving this?