Recommended software: iiUsage
For those of use below the equator (where data allowances are still measured and capped), monitoring bandwidth usage is usually a case of logging into to ISP control panel page. iiNet, for example, have Toolbox – a reasonable utility, but a pain to login if all you want to know is our current data usage.
Note that pretty much everything you need is available at a glance. Whilst the relatively compact application can be minimised to the Window System Tray, I find that it’s light enough to just fire up when you need An it.
I have heard discussion of a RSS feed version of the service, but I beleive this relies on iiNet actually getting around to publishing and XML stream of data (for each user?) – something that’s barely in beta, and judging from their still-woeful billing system, not a priority.
Images used with permission.