Hmmm... Had a bit of a think about this one. We have some things that we could do with a hand on but don't have the time to do ourselves nor the budget to put out elsewhere. This stuff is mainly developing internal tools for our penetration testing team. If you're a Uni student looking to expand beyond a straight CS degree or go into pen testing or information security I can think of worse ways to spend your summer than helping a bunch of guys out with projects, probably wangling sponsorship for government clearance and getting to help out on real world pen tests - then of course if you do well there might be a job when you finish uni, or at least a set of industry references.
I agree that exploitation is wrong, but the key is to find something that pays you back in ways that will help you, and money isn't always the best way to get paid.
But, at minimum, that university student would need room and board ---plus income to service debt--- to work with you. Not all people have trivial access to that even small income ---particularly if their family does not live in the metropolitan area.
This doesn't mean that unpaid internships shouldn't exist if they otherwise couldn't exist as paid positions, but it does mean that some empathy and social awareness to offer even a couple hundred dollars a week, plus lunch, would help many young people "find something that pays them back in ways that will help them."
I agree that exploitation is wrong, but the key is to find something that pays you back in ways that will help you, and money isn't always the best way to get paid.