Granted it’s not just Science Fiction TV shows that inspire obsessive fans and even conventions but I’d say for a sitcom, The Office is headed well into Star Trek territory now and is creating a cult fandom that ranks with anything Star Trek or Star Wars have to offer.
For starters The Office is having a convention to be attended by some of the actors. I don’t know of any non-SF show currently on the air doing this. There are people who specifically visit Scranton, granted people did that with Northern Exposure’s Cicely but in much smaller number. And at least Alaska makes sense as a tourist destination. Though I believe it was actually Washington State. Scranton is virtually anti-picturesque but then the essence of fandom is irrational devotion.
But now The Office crosses into true Star Trek territory with fanfic. I’m sure there’s some deranged people who According to Jim fanfic but for a mainstream show and its mainstream fans to behave this way is decidedly far more suggestive of SF fandom than anything else. From conventions to fanfic to tourism, The Office is looking decidedly outer spacey or at least its fandom is.