The rapid growth of online videos, music and games has created a new Internet sin: using it too much.Comcast has punished some transgressors by cutting off their Internet service, arguing that excessive downloaders hog Internet capacity and slow down the network for other customers. The company declines to reveal its download limits.
http://www.washingtonpost.com/wp-dyn/content/article/2007/09/06/AR2007090602545.htmlAlso see:

Heavy Internet users unplugged by US cable company

Several Internet users in the United States have been unplugged by their service provider because they download too much, a press report said here Friday.Cable Internet and entertainment provider Comcast “has punished some transgressors by cutting off their Internet service, arguing that excessive downloaders hog Internet capacity and slow down the network for other customers,” the Washington Post reported.
http://www.smh.com.au/articles/2007/09/08/1188783547699.html