From Dashling @ D-Addicts:
KeyHoleTV is a Windows P2PTV application that broadcasts all the regular Japanese TV channels (with the exception of NHK) and the occasional American channel, webcam, or whatever random thing that might pop up. With this program, you can stream Japanese channels in real-time. The quality of the audio and video isn't that great, unfortunately. The sound can be downright terrible, especially when music performances or loud audiences are involved. But overall, it's decent enough to hold us over until the show is uploaded or a better-quality alternative comes along.
To install, go to http://www.v2p.jp/video/Viewer/ and download the latest installation file (currently version 2.13). It's updated somewhat often, so you may want to check back now and again.
The program is simple and pretty self-explanatory. To watch a channel, double-click the channel you want under the Program tab and you are set.