How to track AdSense clicks free

I've just made a change to this blog and some other sites I run to track visitor behaviour a bit better. The neat thing is that I can now track clicks on AdSense ads or any other link for that matter free. Specifically I can see which ads get clicked on each page which gives me some valuable information about

• the types of products or services that are of interest to readers of this blog
• the number of blog entries that people typically read when on this site
• how long they stay on my site for (but don't worry - one thing I don't know is who you are!)

I'll be posting a page about this free tracking service shortly