tom stoppard is a fredeeky favorite...

and arcadia is a particular favorite:

Christensen also confirmed recently that Lucas got a helping hand with the script for Revenge of the Sith. In an interview with Playboy, he said the rumours about playwright Tom Stoppard working on the dialogue for the film are true.

Stoppard, known for stage works like Rosencrantz and Guildenstern Are Dead, gave the Lucas-penned screenplay a more "human" dimension, Christensen said.