This is a freeware program I wrote that collects usage information from iiNET Australia's xml feed and displays it in mulitple ways. It allows you to track both your current usage and also your usage from previous months.
This program was witten using the Microsoft .net framework but you don't need to worry about installing it (or if you have it), the installer below will automatically determine if it needs to be installed and will download the necessary files and install them as required.