Literature fans may want to take a brief side trip to Tegna where the author Patricia Highsmith (Strangers on a Train, The Talented Mr. Ripley) spent the last years of her life (her grave is in the Tegna cemetery).

BBC: Two days in the Italian Lakes

Maybe you've seen the movie Alfred Hitchcock's classic Strangers on a Train.

FORBES: A dark view

That means users will temporarily join the group of people at a birthday party or rock concert even strangers on a train.

WSJ: Money Rushes Into Social Start-Ups