on your facebook for example - do you have your current/previous jobs listed? home town?
it occurred to me recently that i probably have too much info up there and i was also shocked by how much info people post (obviously people with shit security settings) including things that could be potentially libellous*. at the minute there's a thread on some nugget i went to school with's wall about how a girl in their work has just been sacked for stealing and how "she's getting the jail".
*i appreciate this would be incredibly hard to prove in court