Facebook was started for the college crowd,parties,meetup whatever. As they matured and moved on it became a great tool to network for companies with these new graduates,and so on and so on that now it's used by everyone.
Even though there is an age restrictions it's online so you'll have your friend's kids trying to friend you or a local company trying to get you to like their page.
There are many games that areplayed by millions of people,there is always a new one starting up,from Mafia Wars to Farmville and whatever the new app is.
You can make a page for your home based business and advertise your business and give info on where you are and what you are doing.
It's good to keep up with family and friends,it's good to promote your business or your product.