Well the standard ones of course:

I T Crowd
Big Bang Theory
Father Ted
Black Books

Also, 

Ultraviolet (which I can't find on-line which is a pity)
Green Wing (so good I bought them all on DVD)
QI 
Dr Who 

But more recently:

The Inbetweeners
Misfits 
Sherlock Holmes (the new BBC adaptation)
Dirk Gently (only been one so far, but was very good).
Last Man/Woman Standing. (Ha! I'll show you extreme sports!)

 Herbie