Alias season 2 finale was such a mindsmurf, it was amazing. One of those, "I think I will DIE waiting for the new season" type cliffhangers.

House season 4 finale was epic too. Just about shattered my heart into tiny little pieces. And the season 2 finale for The Office gave me the warm and fuzzies.

BSG series finale made me want to stab my eyes out it was so awful. But I guess that's something for another thread.