SearchMerge: Social Search in Real-Time « AltSearchEngines
Real-time search has become extremely popular with online searchers. SearchMerge allows you to search sites like Google, Twitter, FriendFeed, Flickr, and YouTube, all at once. To identify which search engine the result is pulled from, SearchMerge adds a small logo next to the result. The homepage gives you the option of choosing an individual search engine or selecting them all. Just recently they have added Last.FM, Vimeo, and Technorati to their list of sites you can pull in results from. You have options to search by normal search or "I’m Feeling Lucky".
Source: www.altsearchengines.com