nonprofiteer writes "With a program called Screenwise, Google is offering a total of $25 in Amazon gift cards to anyone willing to install a Chrome browser extension that will let the search giant track every website the user visits and what they do there over a year-long period. Google says it will study this in order to improve its products and services. Forbes points out that $25 in Amazon credits isn't quite enough to buy a six pack of Marshmallow Fluff ($26.75)."
The money isn't much as a pure trade for privacy, but I suspect that many people would like to have their preferences be among those that shape how Google — and other companies, too — actually organize their interfaces. (Note that the tracking can be selectively turned off by the user.)