Elise Garber married the first boy she ever kissed. She met him at an Outward Boundstyle summer-camp program when she was 15, she "sort of dated" him for the summer, and then, like most teenage romances, it ended. Twenty-two years later, they met again on Facebook.
"I don't know why I looked him up," says the 37-year-old former advertising-agency executive in Chicago. Garber was showing a co-worker how Facebook works, and to demonstrate the search function a feature that allows users to search for the names of people they know she entered Harlan Robins, the name of the first...