I like social networking, it lets me stay in touch with friends around the world. But I worry about the emotional impact it has on people.
A recent study suggests that showing people positive or negative news stories alters the mood of the posts those people go on to write. An obvious finding, but how this was discovered is a bit suspect. The users being studied didn't know they were part of an experiment at all!
Stories like this make me rethink how much I want social networks to know about me.