Australia here, I have a 500gb cap on a 100/2mb line. It is pretty easy to go over 250gig. Especially since our upload and download is counted.
I usually hover around 200-300gig assuming no extra things come up. I don't have cable tv and only recently even bought a tv that could handle Digital signals and still don't watch it. Download everything, and watch it.
Wish more companies would release their older content at cheap prices, many shows I want to watch from the past but I can't find on dvd let alone via a online store.
Caps blow, but they aren't too bad when they are the right size for your requirements. I don't support caps, just know in Australia they aren't going away.... Even our "unlimited" plans on dsl have limits here...