Firehand has an excellent article on light bullets and loads in centerfire rifles, or as he likes to call it, Survival-situation shooting rifle loads. Here's a taste to whet your appetite:
Basic question is, "Why screw around with those light bullets and tiny charges?"
The ultimate concern on this would be 'Everything's gone to hell. You need to deal with varmints raiding the food supply, and small game, but you only have a centerfire rifle with you, or maybe some of the stuff is larger than I trust a .22 for.' They're also good for Low-velocity, low-recoil, low-noise loads for small-game hunting, training a new shooter, and reducing practice costs.Now go read the whole thing.