The Power Debugger plugin has been my personal favourite.Â This version is now compatible with Firefox 5 and Selenium IDE v1.1. It also includes some refactoring to bring improvements from my latest plugins. You will get it automatically when AMO approves it. If you want it right now, you can get it directly from the version page on AMO.
I found a couple of issues while using the power debugger plugin, but they don’t seem to be caused by the plugin itself. I will investigate it further. Let me know if you face any issues while using this plugin.