This one has a very large database, which is good, but if you are searching for someone armed only with a common name, you’ll get an unwieldy result. ZabaSearch also provides historical address information, home address, birth date, phone number, and the ability to contact the person by email.
Spock's best feature is information about a person’s footprint on the Internet, rather than basic details like phone numbers and addresses. Spock draws info from blogs, Wikipedia articles, photo sharing sites, social networking sites (Facebook, MySpace, LinkedIn), social bookmarking sites, and more.
Like Spock, Yasni gives you a picture of the person on the Internet. Unlike Spock, however, Yasni will email you if your search name is mentioned on the Internet. (Of course, you can also use Google Alerts for this.)
Pipl does a “deep web search” to find all kinds of information about someone, from their address and contact info to any publications they have ever posted to the Internet.
123people shows pictures of people, so you can quickly filter out all the wrong people. It also lists out all the email addresses it can find.
Hat tip: Online Tech Tips