Combining the world of search and the world of microblogging, including Twitter, is a popular thing to do these days. With Twitter Search having its hiccups, entrants like Twazzup, OneRiot and TweetMeme have all joined the game of trying to find the best content on Twitter, or finding the most influential users. In the last few days, Topsy, which bills itself as a "new kind of search engine" powered by the social Web, has gotten a good amount of visibility, especially due in part to an aggressive recommendation from Michael Arrington at TechCrunch - who is a big fan.
Topsy is interesting in that rather than finding the best result due to external hyperlinks or having "one right answer", as Google and most other search engines do, Topsy instead relies largely on the number of times a URL is shared (or tweeted) around that specific keyword.