Coupling (United Kingdom)
It's a sitcom, kinda like Friends, except take out all the parts that didn't have to do with sex. It's got some pretty insightful ideas about male/female relationships, although it got kinda stupid in the final season after Jeff left. The show was created by Steven Moffat, who wrote many of the most popular episodes on the new Doctor Who series. Also, Jack Davenport (James Norrington in the Pirates of the Caribbean movies) plays the show's nerdy, whiny leading man, Steve.
Red Dwarf (United Kingdom)
I've actually been rewatching my DVDs of this show and I'm still surprised at how well it's held up. It's a sci-fi sitcom about Dave Lister, the last human alive in the universe. Since the entire rest of the ship's crew was killed by a radiation leak, his only companions through the weirdness of the cosmos are Arnold Rimmer (a holographic recreation of his hated dead roommate), the Cat (a lifeform that evolved from Lister's pet cat), Holly (the ship's senile computer), and Kryten (a fussy robot butler). Although the show featured a bunch of outlandish sci-fi plots, the core of the show was the relationships between its lead characters, particularly the constant antagonism between Lister & Rimmer, sort of an outer space Odd Couple.
The Prisoner (United Kingdom)
This is actually an older series, from the late 1960s. It only lasted 17 episodes but it got a proper ending. Patrick McGoohan plays a British secret agent who resigns from the service. After he resigns, he finds himself captive in a bizarre, psychadelic colony known only as "The Village." No one in the Village has a name, only a number. McGoohan is Number 6 and constantly finds himself in a battle of wills with the chief administrator, Number 2. There is a different Number 2 in almost every single episode. The episodes alternate between Number 6 trying to escape from the Village and trying to bring it down from the inside. In some ways, the show was a prototype for Lost. No one can call himself a self-respecting sci-fi fan without having seen The Prisoner.
Made in Canada (a.k.a. The Industry) (Canada)
This Canadian sitcom is one of the funniest shows ever made. It's about unscrupulous Canadian TV producers who make schlocky shows like Beaver Creek & The Sword of Damacles. In some ways, it was ahead of it's time. It had the kind of dry humor & single camera set-up that are used all the time now on shows like Arrested Development, The Office, & Scrubs. (In fact, it predates Scrubs & the original British version of The Office by 3 years.) It ran for 5 seasons. Unfortunately, only the 1st season is available on DVD. Still, it's better than nothing. I wish I could sell this show better but it's just too brilliant for words.