I am one of the folks working at Stellar. Yes, FB isn't a login method that will work for everyone. But today is our first day saying hello to the world; we do plan on adding more methods soon. Thanks.
A few suggestions (which would probably need to be limited to over X age):
* Google accounts
* Github accounts
* Twitter accounts
* bitcoin-otc accounts (probably with a minimum reputation)
* GPG keys with some minimum threshold of age and "signedness"
* S/MIME certificates from issuers that verify government ID.
I'm guessing the difficulty with supporting multiple methods is a desire to limit this to 5k/person. I'm not sure there's a good solution to this, though I will say that you may have just added some additional incentive to steal Facebook credentials.
