Lately I've become completely addicted to Six Feet Under. Good dark comedy slash drama, real characters and development, sometimes a bit dark and cynical, but I have to admit liking it A LOT!
Otherwise, my number 1 series of all time is the unbeatable Twin Peaks. Nothing short of brilliant.
Also agree on The Office. I'm sorry for American fans of this series, but the only really funny one is the original, British version.