I got some funding and some co-founders... and then sort of floundered (too young, too inexperienced, too big a task).
The fact that this problem has not been solved still gives me a little heart :)
So the question we went for was "can we build a trust based social network where peoples interrelations helped show others how trustworthy (aka sound) they are".
The long term idea was to kick of a trusted identity scheme and wrap a social network on top. The build out from that was a social dating site which we would monetize.
It failed for a few reasons. The concept wasn't well defined, and neither was the problem in all honesty. We were excited about the tech and less so about the execution, spent a lot of time working on the caching code and some framework code etc. and not enough time executing the idea. We never launched (though we could have a couple of times).
The other problem was that the idea would have synced with the tech crowd - but probably less so with the mass market, and we didn't put any thought into how to get the idea across to them.
It wasn't a total failure; I sold some of the code to another social network startup for a lot more than it was worth. They were a VC backed outfit that floundered shortly afterward - so I wasn't the worst example out there :P