I don't watch TV shows much so I am sure I'd like some of those being bandied about, and the only reason I got Firefly is I liked the movie Serenity enough to get the series without having seen an episode before.
simpsons - season 2
family guy - season 2
the critic - entire series (haha, 2 discs before it got canned)
frasier - seasons 1 - 9 (excellent gift from the wife)
I just went to Fry's Electronics and bought the entire series box set of the classic "Monty Python's Flying Circus", called "The 16-Ton Megaset". All the seasons plus some bonus stuff that came along with it...for only $69.99.
Not a bad price, considering that last year, PBS was offering the same package for nearly $200, and Tower Video (during their liquidation sale) was selling it for that same price.