Here is a link to a site where you can send personalized cards to soldiers currently serving overseas. The cards were designed by U.S. schoolchildren. You pick the design you like, add a pre-printed message or write your own, and Xerox prints and sends a shipment of them out to U.S. soldiers every day until Christmas.
What better was to show your appreciation and say Merry Christmas to those serving in a country where open displays of celebrating Christmas are not allowed, unless on a military base (which has m.p.s)? They may not get to have a tree, but at least this way they'll get a message of thanks and Christmas well-wishes while they're away from their families.
I sent quite a few. I don't think it matters how many you send... I sent four I think. Why not take 5 minutes and send a dozen? I guess that means I should send some more!
Xerox U.S. Military thank you Christmas card link