I have Comcast, I've heard it is 250GB a month which means you have to dl about 6MB per minute nonstop for 30 days just to hit it so it is hard to reach it.
Im on 8mb Sky at home and they really dont care...its awesome!
Im on Virgin Media at uni... dont know if theres a monthly limit...but if I download 500mb between 17:00 and 21:00 they half my speed from 2Mb to 1Mb its a pain!
Man all this limited stuff reminded me of me old Dial Up ISP, Pacific Internet. My dad didn't know jack about the internet and so did I at that time. We could only get use the internet 10 hours a month! Basically it was for email only.