Typical Home Bandwidth Usage

Broadband writes: With a growing number of internet service providers imposing hard bandwidth caps, I too will soon find myself with a limit. In typical Slashdot fashion I use the internet for everything from movie streaming to online backup and just realized I have no idea how much data traverses through my pipes on a monthly basis. While I have wizened up and installed a bandwidth monitoring solution, it'll be quite some time until I have a normalized average. So my question is: What is the average monthly data usage in your household? How many people share the connection and is there anything you've found essential yet bandwidth intensive that you couldn't live without? (eg. VOIP, movie downloads, streaming audio, etc)