The Wikipedia article on the Winter Solstice (which happens sometime tomorrow) has a good section about “paralleled traditions” for celebrating the solstice in many cultures. I especially liked the part about solstice celebrations really being a therapeutic device to cope with winter:

“…Being indoors causes negative ion deficiency which decreases serotonin levels resulting in depression and tiredness. Also, getting insufficient light in the short winter days increases the secretion of melatonin in the body, off balancing the circadian rhythm with longer sleep. Exercise, light therapy, and increased negative ion exposure (which can be attained from plants and well ventilated flames burning wood or beeswax) can reinvigorate the body from its seasonal lull and relieve winter blues…Midwinter festivals and celebrations occurring on the longest night of the year, often calling for evergreens, bright illumination, large ongoing fires, feasting, communion with close ones, and evening physical exertion by dancing and singing, are examples of cultural winter therapies that have evolved as traditions since the beginnings of civilization.”
Whether your celebration is therapeutic or not, remember that the worst is over. I’m going to light a candle and get some negative ions now.