There are literally hundreds of different television stations currently available online for users to watch for free. Some of them include public broadcasters from countries including Canada, the US, countries in Europe and very popular are stations from China.
Some of these channels can be played using online streaming technologies such as Windows Media streams, though others are proprietary formats on peer-to-peer networks from across the world.
These software players generally connect to different sources and play back television to your computer screen. What's better is when you have a media server which can stream online TV streams to your real, physical television. Many consoles such as the XBox 360 and Playstation 3 can do with this VLC Media Player combined with TVersity.