This seasonal contravention can take many forms, of which the most ebullient is the holiday cocktail party. The most important part of any cocktail party is of course the cocktails, and here your personal budget enters the picture. Although it would be nice to provide your guests with Lavagulin highballs, Courvoisier sidecars, and Puligny-Montrachet spritzers, sometimes a lesser lineup of beer, wine, and liquor has to suffice. Several microbreweries put out a holiday beer every year, and three or four different brands make for a nice selection. Since many of your guests are sure to bring along a bottle or two of vino, a couple of starter bottles is all you have to invest in.
As far as the rest of your bar goes, it's been our experience that the world has changed since The James Beard Bartender's Guide was published in 1949 with its injunction to invest in nothing more than a bottle of scotch, a bottle of rye, a bottle of bourbon, and a bottle of gin. Nowadays almost everyone wants tequila or vodka in one form or another, but it's a good idea to have the renascent gin, vermouth, bourbon, scotch, and rum around too. The more oblique cocktails demand a selection of liqueurs as well, and although there's an unlimited variety on the market, all you'll really need is an orange liqueur like Triple Sec or Cointreau and maybe Kahlúa and creme de cacao.
Mixers are more crucial; make sure to have plenty of tonic, seltzer, and ginger ale on hand as well as orange, cranberry, pomegranate, and grapefruit juices, and lemons and limes for squeezing (the bottled stuff demeans any good cocktail). Throw in bottles of Rose's lime juice and grenadine, a carton of superfine sugar, pearl onions, maraschino cherries, green olives (preferably stuffed with lemon peel), whole cloves, stick cinnamon, and a variety of sodas for the teetotalers and you're ready for just about any eventuality. And for god's sake don't forget the ice, about three times as much as you think you'll need.
Set up the bar in a central location with plenty of glassware, a mixer's guide, and gadgets like corkscrews, shakers, and swizzle sticks for your guests to play with. You might also want to offer a drink of the evening over on the appetizer table -- perhaps a bottle of aquavit encased in ice (just set the bottle in a coffee can, fill it with water, and freeze overnight), surrounded with shot glasses and canapés of smoked salmon, sour cream, and fresh dill on good rye, or the easiest eggnog on earth -- a half gallon of Bud's eggnog ice cream and a pint of chilled Southern Comfort in a punch bowl, nutmeg, grater, and glasses alongside. Your guests will be joyeux in no time.