A while back I was bored and wanted to take a look at the gRaphael JS library, so I made a quick dot chart of our order totals by day of the week.
Here it is!
You'll need to download both the gRaphael library and the dot graph library both from the graphael website and place them in the admin/includes/javascript directory. Our file uses the non-minified version of the dot library, use the minified version if you want to save bandwidth.
Then just upload this file to your zencart admin directory and navigate to it!
Dot charts are a great way to try and look for visual patterns you may miss otherwise.