Among the few staples of holiday entertaining that seem never to fall out of fashion are nuts. Buying in bulk for parties is the wisest approach, and one source that's proven to offer some of the lowest bulk nut prices in the area is the Nut Pantry just outside the Ballston Metro stop (4227 Fairfax Dr., Arlington, 522-NUTS). The hefty tin canisters lining the shop's walls hold all the familiar varieties, from almonds to walnuts, and many are available in both salted and unsalted form and covered with chocolate or carob. The Nut Pantry's "munchies" also encompass dried fruits, including banana chips and nectarines, Japanese noshies, wheat hearts and fruit-and-nut mixes . . . Another time-honored holiday tradition is still being carried on at Gifford's. The shop's freezer cases are stocked with rum-raisin ice cream "wreaths" big enough to serve 8 to 10 people ($7.25) and ice-cream rolls with centers shaped like a bell, tree or Santa that serve seven ($3.55). The kitchen needs three days' notice to create single-serving ice-cream molds (90 cents each) that resemble Santa, a bell, a tree or a snowman. For the party punch bowl Gifford's makes lime, orange and raspberry-flavored ice punch bricks with pineapple pieces and cherries frozen inside. Each quart brick costs $2.75. Add it to two quarts of ginger ale (or other mixtures), and it should make about 50 servings.