What's Enough Gun
Sven over at Coyote at the Dog Show has an excellent post on stopping power both for handguns and rifles.
Personally, i think the hunting situation he discusses is the perfect excuse for a .416. But then i've had a bee in my bonnet for a .416 for some time-- just can justify it for whitetails.
This, on the other hand, might be a legitimate choice-- 9.3x62.