It's a simple concept: Advertisers want you to see their ads. A "get paid to surf" company pays you to view ads--displayed through a toolbar that takes up about 10% of your computer screen. Keep in mind that you're always in control of whether you want the bar to be displayed or not.

It's also important to remember that a big downturn in advertising revenue (when the dot-com bubble burst in 2000) forced almost all of the companies to fold. One company recently made another go at it and failed miserably. In fact, only one worthwhile company remains.