The core problem: anyone can introduce a social media app that ties directly into Facebook, Twitter, Foursquare and other popular services designed primarily to profile and track consumers to better sell advertising, says Craig Spiezle, executive director of the non-profit advocacy group, Online Trust Alliance.

There is little stopping application developers from “combining and appending” personal data extracted from multiple sources. The goal: amass profiles of users’ online behavior and preferences for advertisers. “Individually these may appear to be like a few pixels of a photo, but when combined can provide a comprehensive mosaic of a user,” says Spiezle.

You download a social media app when you click a Facebook “like” button embedded on a friend’s blog, participate in an online poll, or try out a new wordplay game, says Michael Fertik, CEO of privacy services firm

Read more about privacy concerns with social media apps.