I just joined LinkedIn, a Ryze-like serviced founded by Reid Hoffman, former COO of Paypal.  What I can't figure out is the revenue model for companies like Ryze and LinkedIn.  I had a similar social network-based business idea for a while, but it was limited to specific industries and groups of people and had a per-project profit sharing.  LinkedIn and Ryze are more general so I don't know how peer-pressure for profit sharing can be applied here.

UPDATE: According to Joi Ito, Reid was not the COO of Paypal, but an EVP which I assume stands for Executive VP of something.  *shrug*  I still don't think there is any money to be made there.  In fact, I don't think there is anything of substance in so called social software.  Hype and rush will leave the market severely fragmented and no critical mass for anyone.  I maybe proven otherwise, but that is my view at this time.