As online downloadable video becomes mainstream, it may become difficult to find the shows you like to see on television. There are many sites popping up everywhere that provide noteworthy solutions to this problem, and as some are still in the early stages of development there may be some gaps where episodes of shows are missing. Some of these sites are providing video content illegally, and some are not. Then there are those that contain a mix of legal and illegal content. Anyway, it's all laid out for now in the sites listed below.
Don't forget though, music came before video, and there are some very good audio content streaming and download sites as well. Of course there's always 3pm which was formed as a NET9 project. Others are listed in the links below as well.
Adult Swim Fix
Cartoons on YouTube
Google Video (Beta)
Sci Fi - Pulse
TWiT 55: So Sue Me
Buzz Out Loud - 05.22.06 - On PERL and Pearl Jam