What it does: Displays text, image, and video ads based on your site's content

What's cool: Its smart technology and huge pool of advertisers typically translate into above-average payouts. You can block competitors from advertising on your site by blacklisting their websites.

Drawbacks: It doesn't let you approve ads before they run on your site. In fact, because Google's ads are based on your site's content, there's a good chance the ads will tout goods or services that compete with yours.

What it pays: Typically from 5 cents to $15 a click, depending on the content in the ad.

www.google.com/adsense