Amazon associates is a program that you need to apply for it is not that hard to get approved just be honest with all the information you give. They pay commissions on what is sold through your associate link.
Ebay partner network is basically the same as Amazon, you advertise things on your website that are available to buy on Ebay and when someone purchases through your link you get a commission.
CPA affiliates is a global advertising company, you choose which adverts you wish to display on your website. Generally there pay scheme is based on pay per lead.
Google Adsense is an global advertising platform, which after you have been approved they show adverts on your blog/website and you get paid every time someone clicks on an advert.
Qadabra is another advertising platform which shows adverts on your website once you have been approved, not as hard to get approved for and they have a minimum $1 payout.