(spoilers a-head)

Probably the best Futurama episode, with the only real contender being the introduction of Zap Brannigan. The plot: An accident in a mine causes titanium prices to skyrocket. Bender's body is mostly titanium, so he pawns it for a big fat wad of cash. Richard Nixon's head gets ahold of Bender's body and runs for President of Earth, winning. It all comes to a classic end-the-episode-in-style ending, in which Richard Nixon's head, atop a gigantic mecha-robot, smashes his way into the White House while "Hail to the Chief" plays. There's also a great moment when Bender is selling his body in the pawnshop, and Fry asks "how much for my body?" "Fifty dollars," says the man. "Fifty dollars?!" sez Fry, "My *clothes* are worth fifty dollars!" In the next scene, Fry is naked.

Other classy quotes:

(Fry and Leela are scaling the Watergate Hotel, Bender's head is slung over Fry's back.)
BENDER: (Through hotel window) "Woah, mama! Get a room, you two."
MAN: "We're in a room!"
BENDER: Well, then, lose some weight."

(after selling his body, Bender's head is tossed out into the street, his mouth holding a fat stack of money)
BENDER: "Game over, losers! I have *all* the money! Compare your lives to mine and then kill yourselves!"

Futurama Episode Guide