The gadget is really great, but I missed some features. If you have always the same list in the same order in your sidebar, users very quickly ignore it. But if you shuffle the entries, the list looks fresh every page load. And I could not tell, which one of my most popular posts is the best, they are all good ;) and so random order suits them better.
So my first hack (more coming along) for the Popular Posts gadget randomizes the order of the popular posts. You can install this by adding extra HTML/Javascript gadget in your sidebar or paste the code to an existing gadget (the gadget must be after the popular posts gadget!), or you can put this code in your template html, just before </body>.
I use a simple but effective Fisher-Yates/Knuth shuffle to shuffle the posts. You must have jQuery loaded in your page for the code to work. If the script did nothing to your popular posts list, try adding the following code, which loads jQuery, in your template before </head>:
<script src='http://code.jquery.com/jquery-latest.js' type='text/javascript'></script>
I'm very pleased with the result of the hack, and hope you like it, too. You can see a working example of this in my MS-potilas blog ("Popular Posts" is "Suositut artikkelit" in Finnish), and later I'll install this also on YABTB (now installed).