How Much Would You Pay For Free?

How much would you pay to use Twitter? How about Facebook? Gmail? Would answering a simple "How much would you pay for it?" question help us to understand how the valuable is perceived differently from the disposable? I was going through a credit card bill and among the usual sad thoughts the activity conjures there was one relevant to this blog. There are a lot of online services out there, and I'm actively using a fraction of them. I pay for some, but many are free. The question is, why am I