The DeepOnion bounty (it's not really an airdrop) was really nice until they changed the rules. Now I'm not too keen.
The DeepOnion airdrop is actually pretty cool though I have not signed up for it. Heard from a couple of friends that it is awesome and they each made several hundreds of dollars with minimum time investment which peaked my interest. Went over to their ANN and observed that it is a bounty campaign and not an airdrop, but I find no problem with that. Still not better than the epic bounty campaign by Populous token though.