I know its only October but its never too early to start planning for the holiday season!

I found this handy chart for mailing deadlines if you are sending mail to personnel overseas:

If you don't have anyone specific that you know to send mail to, you can try one of these organizations who provide letters of support to our troops:

http://www.letterstosoldiers.org/

http://www.anysoldier.com/

There's also Operation Ensuring Christmas which provides financial, moral, and rehabilitative support to children of the fallen - http://www.opchristmas.org/