For me, 'networking' only really helps me when I've worked with the people. Nobody you just met at a cocktail hour with name cards is going to call you up if they have a job opening.

If you worked with someone for a few years, they will remember you when a job opens up and call you. Or at least help you when you call them.

Ideally you will have a job/internship with these people, but it works pretty well in a partnership or customer/client relationship. It even works within an open source project (though that is fairly CS specific).