ZoomInfo

ZoomInfo is a free people search engine that scours the Web for information about people, and nothing else. Trying to find people using a general search engine such as Google brings back a ton of results, however, those results can take a while to filter through and they’re not always good. ZoomInfo takes care of this problem by focussing in one niche: people

http://www.zoominfo.com/

What’re they saying about ZoomInfo:

• searchenginewatch 
• mashable
• crunchbase