I think that someone should start a company that buys up these cancelled shows and either continues them or at least provides closure with a 3 part mini-series. They could also presell the DVDs on Kickstarter to get some capital.
Here is my list of ones cancelled too early.
Firefly (brilliant show - every minute a joy to watch and some of the best lines ever - and an awesome ballad for intro music.)
Legend of the Seeker