Top 4 TV Shows That Were Canceled Before Their Time:
1. Firefly. I think there wasn't enough attention paid to this show while it was on the air, and it gained more of a following by word of mouth over time. Witty, funny, and entertaining. You really care about the characters and the plot keeps you interested.
2. Lie to Me (maybe... I'm not sure if this was officially canceled or not. If they do cancel it, I feel they need to do a real season/show finale that ties up some of those loose ends. AKA, I want Lightman and Foster to get together.)
3. Moonlight. This show was really clever, not just another vampire flick. Ok, yeah, there were attractive vampires, but that wasn't the point of the show. I love True Blood like a lot of other people, but that show is pretty much eye candy. Moonlight was legit.
4. United States of Tara. My favorite characters are Tara's teen children- they are smart, capable, and realistic. Kate is sexually active without being a slut, and Lionel is gay without being horribly stereotypical. The family dynamics are great to watch, especially with Tara's multiple personalities and how the family functions (or doesn't) around them.
Alright, this was originally going to be a Top Ten list, but right now, I can't find/think of another 6 shows. I will update the list as I think of things... feel free to leave me suggestions of great shows I missed!