Aaron Sorkin hasn't always seemed like a guy ready to make fun of himself; you'd expect the writer of "You can't handle the truth!" to take himself very seriously. But while picking up the Oscar and other awards for The Social Network he seemed looser than ever. Here he does a terrific little self-referential cameo on 30 Rock, playing himself as a writer scrambling for work because the profession is dying.
Despite the Facebook references, this scene really plays off his television days, particularly the West Wing formula: always walk when you talk and do both really fast.
Here's the episode, with Sorkin at 9:13 minutes in: