Bitcointalk Airdrop
Eligibility :
Jr. Members and above. No negative trust ranking.
From my own personal experience: this is not enough to prevent people from using many alt-accounts to join. Some giveaway hunters have many high-level accounts, and they join with many accounts. I have blacklisted hundreds of accounts already from my own giveaway threads.
I just entered this "world" a few days ago, and it's a pity I can't partecipate to this airdrop because I'm still a newbie