I have been using Topsy for few weeks now, and I am really digging with this search engine -- specifically designed for Twitter. Anyone coming new to Twitter is lost and not sure who to follow and how to effectively use Twitter. The tweets are flowing everywhere, especially in the hot trending topics which may not be off any interest to you. Even with the re-designed twitter that recommends you the top 50 people in each area, you are not sure certain if those people interests you. Google does social searches too, but try doing a search on Google on a particular person you know and try doing the same search on Twitter and Topsy and you will see the difference.
Topsy serves that purpose and serves it well. It's basically a real-time search optimizer in indexing the twitter feeds. If you do a search on Apple, you'll see all the Tweets about that particular link, ranked in order of influence. . The influence meter on Topsy is not based on the ratio of people followed-following, but how active that person is on Twitter and how valuable the person's influence is. A person's influence is determined by how many time he has been re-tweeted.
If you notice, Apple search results brings back the most popular links that have inspired Twitter conversations that are viral. One has the ability to segregate the results by timeline and also country. The links displayed can be shared within the search results.
One also gets the ability to search the top 100, 1000, 5000 and 20000 trending links which would definitely benefit anyone who is new to Twitter.
This is a great website for anyone wanting to know what Twitter is and wants to get started on Twitter. This site is a boon for active twitter users who wants to search on a particular subject. This would definitely get you started on Twitter for sure.