AdSenseAdvisor - 7:46 pm on Jan 24, 2006 (gmt 0)

To clarify, you cannot use language like, "click here" or "click on this button to download Firefox", or display a giant arrow drawing undue attention to your referral button.

However, in the content of your site you could provide an endorsement for the product you are choosing to refer. For example, you might say, "I recommend the Firefox browser." or "If you have a site with lots of high quality text-based content, I recommend trying AdSense." ;)