Understanding your Web site traffic will help you improve your site's revenue-generating potential by telling you what type of ads will work best on your site, as well as by offering advertisers proof that you're getting what amounts to prequalified sales leads. If you have ads on your site such as
Google AdSense, AdBrite, or other off-server ads, you can set pricing and content requirements as you see fit. Be careful though about giving traffic data too freely: You don't want to compromise your users' privacy by selling their e-mail addresses (unless they provide their explicit consent), and you don't want to give away any information that might be of value to a competitor.
For more on Web advertising, be sure to read What Is CPC-Based Web Advertising?