Until recently, very little, now I "zurk" at least an hour per day. Zurker is a new social media platform which is owned by its members. Its open, transparent and democratic. I like to use it because I don't feel as though as though I'm just wasting time and making Mark Z rich!
It's for over 18's only and most of the people I connect with on Zurker are independently minded and also want to have full control of their data and privacy.
The obvious downside is that its still small (about 16,000 members vs Facebook's close to 1 billion!) but it is still in beta so membership will soon grow.
At the moment you can only join by invite- but just do a Google search for "Zurker Invite" to find one.
If you want to know more about Zurker check out my hub.