It was reported from Abu Qutadah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allaah be upon him) was asked about fasting on the Day of Arafah. He said, ‘It expiates for the sins of the previous year and of the coming year.’ Narrated by Muslim.
Most years there seems to be at least one or two interesting coincidences between Islamic holy days and Christian/Jewish/secular/Gregorian ones... this year it is how the Day of Arafat and Eid al-Adha synch-up with Thanksgiving and Black Friday. Interesting. Fasting and sacrifice contrasted with pigging-out and conspicuous consumption.