Farscape and Firefly.
Fortunately, there will be a four part Farscape mini series airing on the Sci-Fi channel this fall. That's better than nothing and at least they'll wrap up that horrid ending they were forced to air.
Fortunately, there will be a Firefly movie. So why doesn't Sci-Fi channel pick up this series? They really need some decent shows--I hardly watch them at all since they dropped Farscape. All the Sci-Fi channel airs are bland, silly, badly-made, badly-written creature feature crap and really lame, poorly conceived series.
Anyway, what I would like to see come back (but never will):
The Invisible Man
The Visitor (the sci-fi series with John Corbett staring)
John Doe (so why didn't the Sci-Fi channel pick this up?! It's cheap to make and better than the crap they usually air)
Birds of Prey
Night Stalker. This is an old old TV series about a man (Darren McGavin asCarl Kolchak)who hunted down creepy things like Vampires and such. I remember I was a kid and everyone in my family would gather around to watch it. Very spooky! It'd be great to see an update of this.
There's a bunch more I can't think of. The shows I like are always canceled. Currently I'm watching Smallville, The O.C. and Alias, fortunately it seems that these are pretty healthy.
-Sleek