I came across this new search site directory while preparing my Social Networking Investigation class. It has been in beta in Europe for months, but expanded to the United States in October. It claims to search Internet-based information in real time, but is also a social site where you can add information to every search result.
The site includes results from social networking information posted on the Internet, telephone and email directories and more. It works best with unusual names rather than common names. If you do not already have some information on the person you are investigating, it is sometimes difficult to eliminate results. But it does include some data I have not seen elsewhere.  
I have added it to the Public Sleuthing links on our web site.