1- Faucets
2- signature Compaigns
3-Trading
4-Gambling
5-Lending
You can search each one of them and see the options which are suitable for you.
For me the best way to source out bitcoins is number 2 to number 3. The biggest provider for me is gambling. The commission I got from gambling is already half btc. I would like to add referral commissions and advertisement to your list. Advertisement and Referral commission is the best source of bitcoin for me. But it is different with different people so whenever we are given an opportunity to earn more we just grab it.