I am doing a long term Star Trek Marathon in chronological order, which is difficult to do given all the time travel. I am almost done with Star Trek: TNG and can finally watch past the intro to Generations. This is just after my 5 year long adventure into every episode of Doctor Who. Makes Star Trek seem easy. 

Uh. The Golden Girls? lol

Not that I have all 7 seasons on DVD and watch every day at least one episode a day.

I also highly recommend Burn Notice, one of the best television shows ever made.

Well you already talked about Star Trek so....

Firefly 

House

Battlestar Galactica

Cowboy Bebop (great anime full of win and the music is great! series and movie)

Eureka

Babylon 5 (haven't seen in it in a long time)

Stargate (holy crap its long and SG1 and Atlantis)

Farscape (also haven't seen in a long time)

Ghost in the shell (series and movies) yes sometimes the animation isn't top quality but still great show! (I want another season damn it)

NCIS 

How I meet your mother

seanw3, how can you watch every episode of Doctor Who, there are some episodes that have been really, truly permanently lost so it is not possible to watch all of them.

The ones that were erased by the Cybermen still have the audio, just not the video component. They put together picture taken of the episode and play them sequentially with the audio. It is still very much better than much of today's TV. 

Man Boston Legal was genius. Kudos to the guy who say NCIS, not the Los Angeles one. However, I got to watch the old series, like Hawaii Five-O, not 0. HIMYM has gotten so off track, I am not sure which stories are just fillers or just a really long way of saying, "kids, I met your mother at a bar, we have sex the first night and got her pregnant, so we went out and we hit it off and we got married."

First two seasons of "24" - really outstanding TV.

HOB series "Carnivàle"

Deadwood.

Prison Break... a good conspiracy-type thriller

Ringer... a good twin bad twin thing with various twists and turns

Games of Thrones is one of the best show. I love this show. This show is running very well and getting good response. I am also big fan of this show.

8 episode miniseries, conceptually awesome SciFi: Outcasts. Give it a try. Might not be your thing. Or then it might.

-Doctor Who (NEW)

-Fringe

-Warehouse 13

-Jekyll

-Torchwood

Last Resort.  I've seen previews of this and it looks quite interesting.  It's about a nuclear sub captain who's given orders to launch missiles.  When he doesn't the sub is attacked by not so friendly friendly fire.

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Black Adder

Game of Thrones

The Walking dead

Fringe