Google expands their video search engine by adding a TV show filter that allows you to sort videos by season and episode. While YouTube and Hulu remain vastly popular, Google's episode search yields surprisingly impressive results.
Google Video doesn't restrict the results to sites that are licensed to stream TV shows, so many videos come from a variety of sources, from Amazon's Video on Demand service to Russian streaming sites (of questionable legitimacy). Unlike YouTube, which also has content restrictions, Google Video no longer has the option to play videos inline. For longer-running shows like Doctor Who and South Park, the episode search filter proves exceptionally useful.
To use it, just perform your search at Google Video (http://video.google.com), then click the Episodes link in the search options sidebar. There's even an option for finding captioned videos!