Since United is joined at the hip with Marriott now I thought I'd post this for those interested.
United is again giving away credit for 10 million miles in its frequent flyer program to various charities, with the amount each gets depending on how many votes it receives between now and Dec. 31. You do not need to be a United Mileage Plus member to participate, and can vote as often once each day.
Several charities dear to the hearts of military-related folks are on the list -- the Wounded Warrior Project and Fisher House -- although there are many other worthwhile ones there.
UA also has an e-miles feature that periodically offers the opportunity to donate money to charity for miles which I often take advantage of and then submit for corporate matching funds.
Wounded Warriors has been offered a couple of times this year, and I donated on each occassion.
If you have not tried this site, I highly recommend you do, as its a win-win for all involved. The charities get donations, and you get a tax deduction and mileage. And if your company does matching contributions, your donation is doubled, and your company gets a tax write-off as well. This year our company asked us to step up contributions as much as we are able to.