For me they'd be...

...Mystery Science Theater 3000, the all-time greatest television show ever produced, ever with a redundant ever. Loved the format -- take shitty B-film sci-fi flick, include a backdrop of a guy and his two robots, let them make fun of it for the next ninety minutes. Pure genius.

...Beavis & Butt-Head. How juvenile, I know right? Every now and again I'll still be up at 3 a.m., pop in one of the DVDs and be spitting milk back into my cereal bowl. Loved this show.

...Tales from the Crypt. Probably the cause of the first nightmares I can remember. Enough said.

...Jackass/Wildboyz. I'm still amazed that these two were cancelled, but I can't say I expected MTV to act any differently. Meanwhile I'll be anticipating a third Jackass film installment whilst watching reruns of Jackass, Wildboyz, Viva la Bam, etc.c

Everyone else?

Powerpuff Girls.

^They made an anime version if you're interested.

Futurama
Arrested Development

*ObZ

Edit: Except Michael Cera is starting to annoy me. He's turned into a bit character; all his roles are the same.

I'm going to take the easy route and agree with these. Tales from the Crypt made me so sad when it was cancelled. :-(

The Job. I loved that show, too bad no one watched it.

Titus and Firefly come to mind.

Tales from the crypt wouldn't bother me if it was at least still in syndication. I could watch the repeats of that for days on end.

R.I.P.

Stella- I fucking love this show, and watch my DVD of the first and only season all the time. It's either hit or miss with this show, some people like me love it and others hate it. The comedy is strange, but still I love it...

Arrested Development- Another one of my all time favorite shows. I own all three seasons on DVD and introduce the show to all my friends and make them fall in love with it. The characters and the story are very captivating.

Old School Nickelodeon- Rock, Ahh Real Monsters, Hey Arnold, Doug, ect... I grew up on this shit and still love it. I can't stand the evolution of kids shows. Nickelodeon is shit now. Another show that wasn't on Nick that I liked a lot when I was a kid was Recess, oh how I wished my school was like theirs.

I'm sure there are a shit ton of others that I can't think of right now, I'll be back with more if I think about them.

Freaks and Geeks.
Bet the fox execs feel pretty stupid now.

Heathcliff the cartoon.
The Gen 1 Transformers.
Get Smart
Wild Wild West

Deadwood, Twin Peaks, Undeclared, Mind of the Married Man, The Adventures of Brisco County Jr, Touching Evil, Lucky Louie, Starved, 3 South, EZ Streets, American Gothic,