Here is their overlay example, it shows percentages as a floodbar.
Here is the heatmap example, Shows the hot areas of user activity.
Here is the heatmap activity for WordPress – interesting eh? Thanks Matt!
Crazy Egg is a genuinely useful tool for evaluating what users are attracted to. Just glancing over the WP heatmap I can see what people are responding to. There are so many social websites with cool use interfaces – Crazy Egg will remove the guesswork from it all and tell us what really works.
Update: I'm using the demo. It's just one (1!) line of JS put into the end of the page. Awesome! Now if I could track the usage patterns in some kind of data format – then I could generate reports of how the usage patterns change as we redesign reBlogger.