"Keeping up appearances" is a 20 year old British sitcom; it's sooooo funny & it used to make me laugh like there is no tomorrow (,")

There's also <em>Black Books</em> and classic <em>Goodies</em> - they have a surprising amount of slapstick and visual humour. You may like <em>The IT Crowd</em> as well.

Oh, and <em>Fawlty Towers</em>! :D

(No interest in Aussie sitcoms?) :)

The Big Bang Theory

I think " How I met your mother " is good one.

Personally I like it.

Respect -Give2Get-

Some of my favourites

Porridge - having a sitcom set in a prison shouldn't be funny right? Wrong, it's one of the best sitcoms ever made. Stars Ronnie Barker, one of the best British comedy actors of all time.
Only Fools and Horses - if you're interested in the London accent and slang this would be a good one. One of the character's often uses rhyming slang, may be a challenge for non-native speakers to understand.
The Office - Perfect sitcom
The Royle Family - Not sure how well the humour will translate to non-native speakers, but I think its hilarious. Good example of different North West dialects.
Fawlty Towers - as has been mentioned one of the funniest shows ever made. I alwayought the comedy was universal, but one of my friends, who is not from the UK watched it and hated it. I think the key to the humour if you understand that Basil Fawlty strongly believes in the old UK class system, and therefore the worst thing that can happen to him is losing face and respectability.