How about a e-mail verification to a bank account with your name on it, along with a credit card or driver's license?
At least, once it was verified, you could not really sign up again with another alias, right?
That would be very difficult I would assume, but if people were willing to do it voluntarily, we would at least know for sure who we could trust, right?
Or who we could at least have some more confidence in, initially, correct? or no?