It may sound ridiculous but there is a way to earn free bitcoin via referral link. Go to kryptomachine: http://kryptomachine.com/?i=68259 and enter you bitcoin address. From there you will receive a referral link, share that with your friends and earn $12.93 on each person that signs up!
While it may not be a scam in your opinion, it could be considered spam. Spam is not appreciated by the community and could be flagged or may result in action from the cheetah bot..
Some things that can be considered spam: