Two months ago, Comcast's fraud department left me a breathless voicemail asking to call them back urgently regarding an "important matter of security."
When I called back, I was told, "We have a bandwidth limit of 250 gigabytes a month. Our records show that in August, you used 710 gigabytes." They told me that if I exceeded 250gb again, they'd cut me off for a year.
Since then, I've started tracking my bandwidth to make sure I don't go over. If Comcast cuts me off, my only alternative is 5Mbps DSL through AT&T, and I wouldn't wish that upon anybody. So, Comcast has successfully used their monopoly position in my area to strong-arm me into lowering my bandwidth usage.
I really hope Verizon FIOS shakes things up soon. It's somewhat depressing that FIOS is available in the boonies of Indiana but not in most of the Silicon Valley.