Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Drupe - Next generation contact manager and dialer.
Bluff My Call - Bluff My Call app provides features to allow users to make prank calls to their friends and family members by changing their voice and caller ID in a few simple steps.
Blacktel.io - Free virtual phone numbers online
True Contact - True Contact is a special caller ID revealing app for those smartphone users who want to resolve their issue of unknown and unwanted calls.
FullContact Card Reader - Automagically scan biz cards into LinkedIn/Gmail contacts