Don't forget that if you're US based, it is likely illegal for you to have unpaid interns. See Mark Cuban's post about this at http://blogmaverick.com/2009/09/05/want-an-unpaid-internship...

The line seems to be this: if your interns are materially helping in the company's core activities, you must pay them. So if they're doing anything other than made-up-work (dig a hole and fill it in), you have to pay them.

I fully understand and agree with this. All work needs to be paid. In our approach, there are some projects that involves our services, but most of them are about build OSS pieces of infrastructure that may use (or not) our stuff, but that should be built for the community in general. We're thinking about stuff like and ActivityStreams mapper, a PubSubHubbub -> Websocket implementation... etc!

Also, funny enough, Mark is an investor in our company and I read this blog post a few months ago!

If you contact your local universities, they put you in touch with interested students.

Interviewing the interns is the tricky part.

Training them can also be more involved than you think. Make sure you have the resources to have one or more people drop their productivity significantly while you bring the intern up to speed. Adding interns is a Mythical Man-Month equation++.

Do you have some suggestions for interviewing interns in particular? I read the blogs on "how to hire as a startup" but none of them really focus on interns.