Scour is a search tool that blends results from Google, Yahoo, and MSN together in one stream. You can hot-swap between the three, or break out any single result into another search. If you come across a bad result, or one you think should go above the others, you can also vote it up (or down) or leave a comment.
Unlike traditional search engines, Scour also has something called Friends Feed, which keeps track of friends on the service and tells you what results they are commenting on. It also rewards users with gift cards for searching, voting, and commenting on good results; doling out points for each user action.
While controversial, and disruptive, the idea of giving users the power to edit search results has become a feature on more mainstream search engines, including Google which added it in late 2008. Where Scour's longevity lies is in blending the results from multiple search engines, and rewarding users that help make them better.