first off, the point of juicing is to remove the fiber so that there is no digestion required of your body. the vitamins, minerals, etc. go directly to wherever your body requires. so on that note, no, the pulp is not necessary for it's "nutritional value."
i personally never use my pulp for anything
however, i do run it through the juicer multiple times if the fruit is especially juicy, that way i know i am getting every last bit of juice.
i never thought of freezing it, isn't that silly? well, actually, i posted about my old refrigerator a few months ago (enough said) i have a new fridge with a wonderful freezer. i shall start saving my pulp and using it in cake recipes and such.
good luck!
peace
hippie