I have to agree with others who’ve said The Office. I’m not usually a huge fan of “stupid comedy”, so I resisted watching the show for a while. After a friend made me watch a few episodes, I found that aside from the stupid, there’s a lot of really clever jokes in there too.
Another one: Battlestar Galactica (the Ron Moore version). I was never big into sci-fi stuff, so when my fiance started watching the DVDs that he had borrowed from a friend, I didn’t really pay attention. But I got hooked, and I mean HOOKED. That show ended up being, in my opinion, one of the best I’ve ever seen. It’s not a sci-fi show per se; I describe it as an intense drama that just happens to take place in space.