I found an interesting site yesterday. It is called world TV PC.com and it has all kinds of subjects including science and scifi. If these are the subjects you like go to science and see the various links to science or scifi tv networks. It also has links to tv series and movies. All kind of subjects.
Free TV, Internet TV Online TV, watch channels on PC, Movies HDTV scifi cartoons adult news
Movies & TV Shows | Online Videos TV shows and Movies Websites
The second link will give you a choice of science or scifi.