Here’s a Custom Search Engine I have created, Hidden Profiles (if you’d like to go straight to the URL, it’s http://bit.ly/hiddenprofiles). This search has become popular due to appearing up high for a Google search for hidden dating profiles.
The Custom Search Engine looks for profiles across many different sites and has refinements for several social networks. Please check it out and let me know what you think.
Another Custom Search Engine: http://bit.ly/findpersons (find other profiles!)