We could organize some kind of bounty on him. Since people are already selling their investments at a discount, I'm pretty sure most of them would be willing to give something like half of their "investments/bets" to a person who tracks this guy down. For a few hundreds of btcs reward, i'm sure many would look for this scammer.
There is a good chance he left his IP address somewhere, like i said, i'm not sure he started this site as a scam, so maybe he didn't use proxy everytime he logged in to this forum or when he registered domains...