Hi Beth,

You can always transfer orphan AA miles to the following loyalty programs:

Alamo® Car Rentals
Avis Rent A Car
Budget Rent A Car
Diners Club® Points
Hilton HHonors® Points
Intercontinental® Hotel stays ( including Intercontinental® Hotels and Resorts, Crowne Plaza® Hotels and Resorts, Staybridge Suites, Candlewood® Suites, Holiday Inn® and Holiday Inn Express®)
National® Car Rentals
Priority Club® Points

http://www.aa.com/i18n/AAdvantage/programDetails/redeemMiles/aaRedeemMiles.jsp

Do you have Continental miles? I believe United and Continental miles will merge in early 2011 so maybe the United miles will become useful to you over time.

Andrea