Perhaps you're already aware of this, but this took me by surprise. You can view entire tv shows from Fox and NBC Universal at Hulu.com virtually anytime! I was aware that TBS did this and supposed many others did, as well, but the ones I've researched don't. (ESPN, I don't remember what else!)
I've found these networks that currently have full episodes offered online, and I'll add to them as I find more:
It doesn't appear that the following networks offer this:
Discovery(including TLC, Animal Planet, etc.)
This is of course a very short list, mostly limited to those channels I can think of off the top of my head that I MIGHT watch something on...very limited indeed!