You can also buy traffic, but be careful what you buy. It's mostly junk traffic, but some people make money off of it.
Popunder and popup traffic is 'crap' traffic, but it's better than 'bot traffic' which is nothing more than a slow-rolling DOS designed to fool advertisers, potential site purchaser and is highly unethical. That being said, many major and minor publications get away with that dishonest and deceitful practice.
Another good way is by producing quality videos and posting them on YouTube.
I have a master-list of traffic sources where you can buy traffic. I'll post it if you're interested.