Best: John Goodman as Robot Santa.
Worst: Beck or Lucy Lui. I don't like guest stars that come on and the *entire* episode revolves around that guest star as an actual person. It is ok if they play a different character, but themselves? That is just ostentacious.
Although it is slightly different in certain circumstances -- example, Al Gore playing himself, but he is the head of the time patrol. This is a joke on a role, not the actual person himself, which is why it worked. With Beck, he only did the show if the episode was about him and how great he was.
Whoops forgot about pauly shore he is the worst,