They used to rerun those every night in syndication on local stations years ago. I think Nick @ Nite did too. I haven't seen them anywhere in awhile. So I wonder if they stopped because they found offering those original episodes on DVD was more profitable when DVD's were all the rage. I seem to remember seeing the seasons available that way in places like Blockbuster.com and Netflix.
Awhile back you could see them all for free on youtube too. But then copyright infringement came into play. So youtube took a bunch of them down and NBC put a few of them up on their own website. Seems to me them doing that was the least profitable way to go about it. They should've kept them in syndication and got the residuals.