Do you live in an urban area? Foursquare has been commonly talked about by the non-tech-savvy people I know for years now. I'd actually say moreso than any social service other than Twitter and Facebook, over the past 3-4 years.
One of the most useful apps on my phone, honestly.
I think it probably depends on your industry. I'm a programmer, so maybe if you're a finance major it's more useful.