In December 2009, a college student named Mia sent Facebook messages to two people named Christopher and Emily, asking them if they had found a baby in front of a townhouse in 1989. Turns out that Facebook aided in reuniting this abandoned baby girl with her rescuers. You can read the story here. (By the way, don't read the comments. Sure, the story isn't written really well, and it ends rather abruptly, but it's a nice story.)