I don't see how this is different from the real world. I see lots of ads for "Unpaid Internships" that want extensive knowledge of the field and expect you to already have the skills and experience the internship is supposed to teach you.
My favorite recent: "We are a couple of mompreneurs who are launching a business geared to moms. We are looking for someone, preferably a mom so you will already have knowledge of the target market, to help us with website design, online promotion etc. etc." http://vancouver.en.craigslist.ca/rds/cpg/1621222670.html
I think I'm going to try this stunt with every service I consume. "Yes, you see, you give me a haircut for free and then we split any resultant profits. 70-30, because the haircut was my idea".