Family, friends, neighbors, employers, and social media platforms are all good sources of actionable intelligence about an individual, but, for good reasons, people are typically not forthcoming with the information you wish to gather, and searching every social media platform is impractical and inefficient. That's where websites like SocialMention.com and Social-Searcher.com may be helpful.
Social Mention is a real-time social media search and analysis platform that "aggregates user generated content from across the universe into a single stream of information. It allows you to easily track and measure what people are saying about you, your company, a new product, or any topic across the web's social media landscape in real-time. Social Mention monitors 100+ social media properties directly including: Twitter, Facebook, FriendFeed, YouTube, Digg, Google etc."
Social Searcher is a free social media search engine. "It allows you to search for content in social networks in real-time and provides deep analytics data. Users can search without logging in for publicly posted information on Twitter, Google+, Facebook, Youtube, Instagram, Tumblr, Reddit, Flickr, Dailymotion and Vimeo. Free users can also save their searches and set up email alerts."