A very great airdrop on Coinbase is always available.
You can follow short explanatory videos familiarizing you with several cryptocurrencies.
A small questionnaire at the end of each video will give you between 10 and 50 dollars in token.
A queue system is put in place to regulate airdrop.
I offer 5 invitations for the EOS training :
http://coinbase.com/earn/eos/invite/x9k31764
And invitations for Stallar Lumens :
http://coinbase.com/earn/xlm/prompt/62qp430g
