I'm also in process of breadboarding around a pre-burned ATmega168.
Picked up a handful of 16 mHz resonators at Digi-Key earlier this week. As I understand it, a couple of filter caps, a regulated supply, and the resonator is most of what I need to get a "naked" Arduino running.
(I'm tinkering on a project where I just don't have space for the full diecimila and shield).