Seth Godin has an interesting post on the idea of giving away products (to the right people, of course) in order to promote them. The innovative thought that Seth has picked up on is to buy large numbers of a similar (but already successful) product, sell these absurdly cheap, and package your product as a freebie. Clever.
"What a shame that Amazon hasn't figured out how to provide this as a useful service. Amazon knows who buys a lot, they know who reviews a lot... why not ask those people if they want a free prize now and then?"
I suspect they have. This sounds a lot like the Amazon Vine programme (that I happen to have been invited to join!). People who have written helpful reviews become eligible to receive free stuff, often the equivalent of promo CDs and publisher's proofs that DJ's or reviewers get. As Seth says:
"...but now, of course, it's us that are the DJs..."