The deleted scenes on the Revenge of the Sith DVD were pretty cool. More Grievous is always a good thing. But a couple of scenes I would have liked to have seen would be some background info on Grievous- back when he was Lieutenant Grievous, you know? And maybe a shot of Darth Vader signing bonus cheques for the Clone Troopers who so ably carried out Order 66. Seeing him struggle with mastering a new signature with his new cybernetic arms would have added a lot to his character development I think.

Palpatine: Good, Lord Vader. But you know 'Darth' is spelled with a 'D', right?
Vader: (shakes fist at sky) Noooooooooooo!!!!!!!!!!!!!!!!!!!!!