Yeah Thucy, more than anything, your argument just points out the DISanalogy to seeing somebody getting stabbed on the street. There, it really is obvious what to do.
As for your examples here -- Draug's point re: food is correct. If we can make sure the food is getting to the right places, then sure, OK, we should help. (I'll leave aside whether it should be governmentally -- suffice to say, the American people should help).
Note that the above is directed to situations of temporary famine: where the cause for famine are systemic, we can do that effectively only if we also have a good plan for ending their causes of famine (agricultural, etc). See: moral hazard. (Yeah, and I don't think we should have bailed out the banks, so please spare me that in your response, if you were planning to go there).
If the government that is there is such that there is actually some hope of agriculture etc. working, then we absolutely should work to get that going. This is probably the most important thing to do. I agree.
As for "10 Americans dying," your point is incredibly offensive. The history of the last century is one of Americans constantly dying to accomplish what we saw as right in other countries (and not just European countries) and, often (more and more), getting condemned loudly at home and abroad and accomplishing little apart from stirring up bad will. But oh, no, we should just run in everywhere with out military and save everybody from their political strife.
Do you even have the faintest idea how your fellow liberals would howl if we started doing that regularly? Of course, yes, it might actually succeed like few other policies could (if done case-by-case, which expense would force to happen) if we could maintain the will to do it. But given the complete lack of any moral or theoretical basis for doing so, short of adopting a full-fledged imperialism that Americans seem little committed to, there is no way it could be practical or sustained.
And again, if you going in and knocking down dictators and then running out and leaving chaos and a power vacuum gives you a warm feeling about yourself, great, but don't pretend it's some enlightened righteous concern for others.