founded by Garrett Camp, Geoff Smith, Justin LaFrance, and Eric Boyd (2001) - San Francisco, CA
StumbleUpon is a Web browser plugin and internet community that allows its users to discover and rate Web pages, photos, and videos. Web pages are presented when the user clicks the “Stumble!” button on the browser’s toolbar.
StumbleUpon chooses which new Web page to display based on the user’s ratings of previous pages, ratings by his/her friends, and by the ratings of users with similar interests. It is a recommendation system which uses peer and social-networking principles.Users can rate, or choose not to rate, any Web page with a thumbs up or thumbs down, and clicking the Stumble button resembles “channel-surfing” the Web.
eBay acquired StumbleUpon in May of 2007 for $75,000,000