I've purchased miles occasionally to top up the account as needed for awards.

Actually right now (through 2/28) AA is giving bonus miles with miles purchased.

Buy the Miles You Need to Get There
And Earn Bonus Miles!
With American Airlines AAdvantage® miles, you can get to extraordinary destinations this year. What are your travel resolutions for 2011? Take a vacation, visit friends or family and immerse yourself in a new culture.

Simply purchase the miles you need to reach your next award and start planning the trip of your dreams. Plus, when you purchase miles through February 28, 2011, you’ll earn up to 15,000 bonus miles!


The More You Buy, The More You Earn!

Purchase Bonus
2,000 500
6,000 2,000
12,000 4,000
40,000 15,000

The link is https://buy.points.com/AAdvantage/i...BuyFeb11&c=AASoloBuyV4DomEngBuyFeb11