This is going quite well - thanks to those who've contributed.
I've sorted the first lot into alphabetical order (OCD) but if any additions are added above this list please so we can see new ones as they arise. I'll pop in to re-sort them every once in a while, okay?

With so many channels available these days I find it difficult to keep up with what's new. I'd find it useful to have a list of 'worthwhile' telly to watch that I may have missed.
If anyone knows of either any new series coming up or decent series [cult status?] worth digging out please list them below. Maybe a separate wiki for UK series? Perhaps if enough interest we could make it a sticky?

Additions:

Battlestar Galactica
Jericho
American Gothic (toasty)
Deadwood (toasty)
Southland (from oj121)
Spartacus (from oj121)

Sorted list:

24
Alias
Band of Brothers
Boardwalk Empire
Breaking Bad
Continuum * SF
Copper
Damages
Dexter
Entourage
Firefly * SF
FlashForward * SF
Fringe * SF
Game of Thrones
Hell on Wheels
Heroes
Homeland
Homicide: Life on the Street
Justified
Mad Men
Oz
Prison Break
Revolution
Rubicon
Six Feet Under
Sons of Anarchy
Suits
The Mentalist
The Pacific
The Shield
The Sopranos
The Walking Dead
The Wire
True Blood
Warehouse 13 * SF