Ask HN: I'm going to a Uni preview day - what can I talk about?

I'm going for a university open-day tomorrow, I'm applying to do CS, and although I'm not being asked for a formal interview I am trying to think of a few topics to chat about.

I've looked through some news sites, compsci.reddit and a few others but nothing's really struck out at me. I do have a web-application I'm developing on the side that I'm prepared to show them if I can slip that into conversation but what are your suggestions for topical stories?