Mining bitcoin is especially viable if you believe in Bitcoin on long term or if you have cheap electricity fees. Regarding faucets I don't think you can say you can make money of it. I mean the amounts are so low that the food you need for your work costs more lol

PTC - the same, but you can gain some beer money per month

Micro jobs - if you live in a developing country you can gain nice amounts, but if you're living in a strong economy state, it will mostly be a waste of time. You will get by much better with a regular job.

Gambling? - That's a way to lose money and have fun, not to make money

Holding Bitcoin - is a good long term strategy in my opinion

Trading - a very lucrative industry, but it requires a pretty big learning curve and A LOT of practice and experience

Affiliate marketing - has always been viable, but again you need some investment first usually.