iiMUM is a
free Windows utility that monitors broadband usage for customers of the Australian ISP
iiNet. Broadband usage is updated hourly with data retrieved directly from iiNet's webserver.

While iiMUM is running, an icon will appear in the notification area of the taskbar. The style of the icon will depend on the type of plan its monitoring. If the plan contains
'peak' and
'off-peak' periods then the icon will have two coloured 'fuel gauge' bars indicating how much of your 'peak' and 'offpeak' quota that you have remaining. If iiMUM is monitoring an
'anytime' plan, then the icon will show a single coloured horizontal bar with a number below indicating the remaining percentage of your monthly quota.

The colours of these bars indicate whether your current downloading is within budget: green indicating that you're within budget; and red indicating that you're likely to reach your monthly quota before the end of the month unless you slow up; and shades of yellow and orange indicate you're somewhere between green and red.
Update: Added support for unlimited plans.
Update: Minor cosmetic changes.
Bugfix: Auto-update was still broken ...
Update: iiNet updated their encryption again which broke things.