TMobile (USA) Minutes Used version 0.9
The new version has the feature to disable the extension from the status tray. This is demanded by many users to avoid hitting the TMobile web site too often when opening new Firefox instances.
You can download the version 0.9 here.
(save the file locally and then open it from Firefox: File->Open File...)
Other popular demands are to support prepaid account or show data usage. Since I don't have either capability with my TMobile service, my account page doesn't show it. I need someone to send my a screen shot (html file) and I will be happy to enhance the extension.