The groups are handy for events or stuff like the kids soccer league, as the schedule is always there, as well as weather cancellations.
Also there is a page for a small town near us, that's just people posting local events, or questions, or bear sightings. Its amazing how respectful everyone is on it, as no one posts junk.
It is entertaining sometimes, I have one friend who basically is the right wing version of John Stewart and his commentary on current events is always good for a laugh, as are the responses.
It does give you a small window into other peoples lives which I find interesting as I don't see many of them for years.