It's all under a general category, monetization.
Adsense is the best of the click ads, don't buy junk traffic they don't accept it and will delete your account. I've heard about 50/50 of the guys trying junk traffic actually losing their accounts. Google will catch up to you just like any other anti-spam will to black hat tricks.
Adsense and other PPC advertisers give you a fair share, but no where near the money you can make from affiliate marketing and list building.
make sure you choose a highly specialized niche best practices.
You can go to niche profit classroom and get the best training I've found out there in the affiliate marketing business. Adam Short at NPC covers adsense, listbuilding, and his tested best practices. Here is another affiliate program I have it's a lot less in depth than NPC, google sniper. And the last one I have is get money here, I don't give out affiliate links to programs I wouldn't do myself, but here is a link anyway if you want it.
http://www.get-money-here.com/
Yes, some of these are my affiliate links, but I think it's an appropriate answer to the question.