StumbleUpon

StumbleUpon is a unique website where users define their interests and then "stumble" the web. Stumbling consists of the web surfer being taken from one randomized website to the next based on their predefined interests. While stumbling users can vote sites up or down which "teaches" StumbleUpon the types of content they like to find. It's fun and entertaining and you never know what you are going to discover next. http://www.stumbleupon.com/