Not included in the list are the network sites that stream their own shows. You can find that list on a Gizmodo Guide called Internet TV Remote. Both of the above lists are accessible to US viewers only.
European and Asian viewers watch TV online on video sharing sites because the networks and third party websites are still working out international copyright agreements. The best link-site by far is Sidereel.com.
Update: Along with hundreds of others, Hacknmod has yet another list, and also references a video Build Your Own Open-Source DVR. For more on DVRs, see Comparison of PVR software packages at Wikipedia.
Update: All Things Digital has some related info in Web Video Winners: YouTube, Hulu…and MegaVideo?