Didn't Matt Stone & Trey Parker pull the plug on this themselves? I remember reading somewhere (I think) that while it was getting good ratings, they just found it too expensive to produce. But I guess it still qualifies as a premature burial. :)
American Gothic (Nearly a full season, but I think some of the final episodes were skipped). Also, Kindred: The Embraced. More recently, Greg the Bunny and Miracles.