. . . SearchBoost, aims to give search ads a boost of credibility by showing the ratings and rankings from others who have downloaded the Web browser add-on, too. Xmarks [add-on] counts more than four million active add-ons in use by people who have downloaded the Xmarks browser add-on. Those users do about 450 million searches monthly.A 30-day test with 200,000 searchers measured the clickthrough rates on ads and found that click-through rates increased by 15 percent for advertisements that showed SearchBoost data. Tests with REI, 1800Flowers, RitzCamera.com and theFind.com afforded similar results.
Check it out here: Xmarks Beta