This month, American is offering up to 20,000 extra AAdvantage Miles when you purchase miles through November 30, 2010. From their website:
Earn up to 20,000 AAdvantage bonus miles when you purchase the miles you need to reach your next flight award.
Do you need more AAdvantage miles to book a flight award now? You can easily purchase the miles you need with the buyAAmiles program! Plus, you’ll earn 2,000 bonus miles for every 6,000 miles purchased, up to 20,000 bonus miles, on purchases made through November 30, 2010.