If you'll pick up some snacks, I'll get the beer.
In this sentence there is used the volitive "will" as I was thought by StoneyB in his exhaustive reply to my latest question here ("Would" in a backshifted reported context). This sentence can be paraphrased in this way: "If you are willing to take care of getting snacks, I am willing to reciprocate by providing the beer". But I am not able to see the difference between this sentence and the standard conditional clause, i.e. "If you pick up some snacks, I'll get the beer". Every conditional clause after all includes a reciprocal aspect. Can you please give me some other examples ot the volitive "will" in the sentence.