This article came off of Slashdot recently. The NY Times Magazine article it references was a fascinating read about a company (or two) that get volunteers to talk up sponsored products. While I'm not that tempted to sign up, the psychology behind it is interesting. I've thought at times about what products I'd plug if I was famous and anyone would listen, and how I'd do it, and this idea comes close.
Nobody gets paid, except perhaps in samples or swag, and apparently only a third of the stuff that could be claimed by the vols gets claimed. The article spends a good bit of time trying to figure out why folks would do this, if they're turning down the goodies. It's a bit longish (9 pages), but again, quite fascinating.