Topsy – Search Engine For Conversations
At the very first sight, Topsy would seem to you as another twitter search tool but it is a much more advanced search engine for conversations.

The Topsy describe it self as :
Topsy is a new kind of search engine, with a new way of looking at the Internet. Topsy doesn’t think the Internet is a collection of documents. Or even a web of documents. Topsy sees the Internet as a stream of conversations.
Topsy listens to the conversations taking place all the time on the living, social web. This is the rapidly growing, exciting world of Twitter, Blogs, Flickr, Digg, Yelp, Identica and many other communities. People use these communities to share reviews, opinions, messages, comments and discussions about things. Topsy indexes those things. Topsy indexes what people are talking about.
I really appreciate tools like SocialMention, but Topsy is much advanced tool. Twitter is the primary searching world for Topsy, but it takes the research beyond it to blogs, websites and other UGC sources.
Topsy has another great tool which is user focused. This is individual conversation page for users. (see my page here)
A similar trackback page for URLs is also available for tracking all the conversations around any webpage. (example)
Hence, Topsy is a cool & powerful search tool.
Check out Topsy
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Nihar Said,
I have seen wolfra also. this is also a good one.
Lots of search engines coming up these days.