Saw one more interesting tidbit on the origins of Black Friday, in today's WSJ:
The day after Thanksgiving is still known as "Black Friday," because it once marked the day when stores moved into profitability and black ink for the year. But these days, retailers are kept in suspense about the size of their holiday windfall until later in the season, as more people put off major spending until the last minute. The Saturday before Christmas had overtaken Black Friday as the year's biggest shopping day, but last year, Black Friday retook the crown. Still, Black Friday's importance as a predictor of holiday spending has diminished.