When I use the word free, it assumes that you have a device that will run the free software, and an fairly quick internet connection.
You do not have to purchase anything. You can download and run the XBMC (X Box Media Center) software on almost any computer – or your phone/tablet (*may need to be jailbroken (see below)). You do not have to own an XBOX.
XBMC with Navi-X has loads of content, but it can take a while to find out what you are looking for. Its like walking into a new hotel room and trying to understand what is available on the tv. The available content is from all over the planet, and all the content is free (live tv, current movies, sports, Pay Per View Events and more).
Is it legal? Clearly a lot of online content is probably posted without proper permission. What you watch is up to you. I have not heard of anyone that has been arrested for watching streaming content that they did not pay for.
>> Install a web interface for even more detailed interaction
If you are installing OpenELEC on a Raspberry Pi, their forums are here.
>> More how-to videos
Demo by Don Clark of Geekspace Gwinnett
>> *Free Streaming TV, Movies and more (my blog)