Free Services
Here are a few free services and methods for watching streaming content online:

Joost
Joost is a free internet TV service created by the team behind Skype. Originally people had to download an application from the Joost website allowing access to their streaming content, but as of December 17 2008, they've scrapped the application and are now a website-only model. Joost offers all kinds of streaming content, such as TV shows, movies and music videos. Check it out HERE.

Hulu
Hulu is a commercially supported website that offers lots of streaming content, such as films, TV shows and music videos. Hulu also offers shows in HD format. However, Hulu is only avaliable to users of the United States. Check it out HERE.

Veoh
Veoh primarily hosts user generated content, however they do provide legal links to TV Network content, as well host a huge library of movies (albeit very old movies). Check it out HERE.