The Demon Hunter in Diablo 3 uses two different resources: Hatred and Discipline. Hatred fuels the DH's offensive abilities, while Discipline is for defensive, evasive, and utility abilities, creating some very interesting gameplay.
Do you think it'd be possible at all to create a Champion who uses two different resource bars? Maybe one is mana, while the other is a unique resource that applies to the Champion itself. Just a thought.