Back in 2001 I did some consulting for CyberRebate, who were building exactly this. In return for running their proxy you'd earn reward points that you could ca

Back in 2001 I did some consulting for CyberRebate, who were building exactly this. In return for running their proxy you'd earn reward points that you could cash in on their site. They imploded (http://en.wikipedia.org/wiki/CyberRebate http://en.wikipedia.org/wiki/CyberRebate) before the product was launched.