I remember seeing several sites try one or more these strategies, the only notable success that I know of is smallworld.net which caters to a market that used to be known as the jet set, rich, well-connected and privacy conscious individuals who want the exclusivity.

But this (validated identity) is the sort of thing that Google, Yahoo and Microsoft keep trying to push out the door (now joined by twitter "verified identities"); and it keeps falling flat.

This is basically what Amazon's "Real Name" system is.