Hulu
Hulu streams high-resolution, ad-supported videos of both television shows and movies. More specifically, the site distributes content by NBC-Universal, Fox, and a handful of their subsidiaries. Popular shows hosted by Hulu include The Daily Show, The Colbert Report, Battlestar Galactica, The Simpsons, The Office, and Saturday Night Live. The biggest complaint leveled against Hulu is its US-only restrictions, though many of you are using previously mentioned Hotspot Shield to access Hulu from outside the US. Hulu isn't entirely US-only, though—the first show Hulu made available to the world at large was Dr. Horrible's Sing-Along Blog, with Lifehacker favorite Felicia Day.
SurfTheChannel
SurfTheChannel aggregates video from all over the internet—including sites like YouTube, MetaCafe, and Hulu (along with much more obscure sites)—then makes all of those videos available through a simple, searchable interface. It's not always pretty, but the selection is huge. The downside: According to the STC homepage, the site will shut down on October 1st.
SideReel
SideReel is a video aggregation site similar to SurfTheChannel, providing links to streaming video from all over the internet. It's an attractive site, but if you're there to find video it can be difficult to navigate to begin with. If video is what you're looking for, just navigate to the Links section of a show's page and click on the episode you want.
Straight from the Source
Apart from the sites dedicated to streaming content, more and more networks are building their own on-site tools for streaming content from the source. For example, the big three networks all have streaming sites: the ABC Full Episode Player, the NBC Video Library, and CBS Video. If you missed a show you're dying to catch online, be sure to check the web site of the network it aired on to see if it's available.
BBC iPlayer
The BBC iPlayer streams content from up to 250 programs from the British Broadcasting Corporation. BBC iPlayer restricts streaming to the UK-only, but like Hulu, setting up a proxy with an application like previously mentioned Hotspot Shield has worked for many people looking to get around these restrictions. [via lifehacker]