Kennett Square's Nathan Egan, a social-media consultant who's worked with such companies Facebook, LinkedIn and Twitter, got a taste of the power of this technology.

In New York on Wednesday, he boarded a train bound for Philly. He came upon a wallet stuffed with $350 in cash, eight corporate cards and a driver's license. Name: Sally Smith Clemens.

Egan, of Freesource Agency LLC, booted up his laptop, found her on Facebook and shot her a message.

Clemens says she called him five anxious hours later, after she decided to check her Facebook account on her handheld to calm herself down.

Egan, who sent the wallet to Clemens' Florida home, says: "I see a lot of the liability in cyberspace, but it can be a space for good work and humanity."