Help EFF Measure Browser Uniqueness
The EFF is doing some measurement of browser uniqueness and privacy. It takes ten seconds.
Before you go, why not estimate what fraction of users have the same
transmitted/discoverable browser settings as you, and then check your
accuracy at https://panopticlick.eff.org. Or start at http://www.eff.org/deeplinks/2010/01/help-eff-research-web-browser-tracking for a bit more detail.