What about forcing new users to pay 0.1BTC on signup and it gets refunded after 10 or so posts if they're not banned for spamming/trolling?
Wouldn't work in my case. I came here hoping to purchase some bitcoins. Wouldn't be able to spend any yet.
But a better method would be appreciated. Like I'll fax you a copy of my passport? Whoops, guess that wouldn't prove I'm me - like this does