Joost recently (within the last couple of weeks) came out of Invitation-only beta.  It’s a program developed by the same people who brought you Kazaa and Skype.  Like those programs it also harnesses the power of peer to peer (P2P) technology.  (Another reason for advocating net neutrality!)  Joost is meant to replace cable TV and provide the viewer with programs on demand.  There are a lot of other people trying to work on the same goals, but a key difference is that Joost actually has deal with content providers to legitimately provide content.  Both The National Geographic Channel and Viacom Channels are available.