There are several professional websites that offer free people searches including People Smart and Ppl, both of which search public records, social media sites and business networks such as LinkedIn. Zaba Search also searches public profiles and blogs to find relevant information about an individual.
Information gathered during these searches includes email and contact information, pictures, a history of past and present residences and Twitter feeds.
While the sites listed have free searches, some like People Search only show limited information and restrict access to the complete details to paid memberships. Some of the enhanced features of these sites let users create alerts and receive notifications when new information has been discovered about someone.