Pay per click

Pay Per Click (PPC) is an Internet advertising model used on search engines, advertising networks, and content sites, such as blogs, in which advertisers pay their host only when their ad is clicked. With search engines, advertisers typically bid on keyword phrases relevant to their target market. Content sites commonly charge a fixed price per click rather than use a bidding system. - wikipedia

Generally, there are two ways to easily earn from this. One is to click ads which is boring for me and while the other is using the referral system. The payout from PPC is normally from Paypal and Alert Pay.

Just remember 3 things; Click, wait and get credited.