He is using the plugin, which is usually for displaying 125×125 advertisements in your blog sidebar, to count how many times his RSS button is clicked. So coupled with the Feedburner subscriber count, he has a metric of how many people actually subscribe to the feed after clicking the icon.
If you’re curious, approximately 21% people subscribe to this blog after clicking the big button to the right.
Interesting idea, Dave. I never would of thought of using an ad plugin to test links’ conversion rates. I suppose it’s not too huge stretch, but it’s quite creative.
It’s kind of fun seeing people use my plugins for things I never intended for originally.