I'm doing a social search engine. Won't be big and professional like Google. This has been brewing for a while, and is starting to get ready. I'd like any feedb

I'm doing a social search engine. Won't be big and professional like Google. This has been brewing for a while, and is starting to get ready. I'd like any feedback on things people like/dislike in it :) Are there any other social search engines that draw from multiple sources? I know there are services like mention.com, but I wanted something where you do not have to sign up and can just search right away.