http://chris.pirillo.com/comcast-250gb-cap-avoid-dropbox-or-online-backup/

Comcast currently has a 250GB data cap on residential Internet accounts in the United States. If you go over this bandwidth cap once and receive a warning from Comcast, exceeding it a second time gets you banned from using Comcast services for a year. Andre Vrignaud was a Seattle Comcast customer before he was banned for exceeding the Comcast bandwidth cap. Here he tells his story and explains what he thinks would be a better solution for ISPs like Comcast in dealing with high bandwidth users