I see alot of you are wanting to support the troops, but seem to be afraid of scam sites and other things. Might I suggest the following.
http://adoptaplatoon.orgThis is a non-profit organization that will let you "adopt" a soldier. You sign up to give support and they give you a soldier and his contact information. From there, you agree to write letters, and send the occasional care package.
I have been doing this for 3 years now. I have supported 6 different soldiers. Last year, I supported a great sergeant who always wrote back and always thanked us for what we sent. Whenever I asked what he needed he would never say, until one day, he asked for a basketball for his company. He said they had found a goal in the some garbage while cleaning out a bombed out school, but they couldn't find a ball anywhere. Off I went to Wal-mart, bought a football, a basketball and a frisbee, boxed them up and sent them over along with a disposable camera. About 3 weeks later, I got the camera back. It was loaded with pictures. Every guy in the company had posed with either the football or basketball to say thanks.
I think this is a fantastic way to help out. You are directly in contact with a soldier and you know that they are receiving your support and they appreciate it so much.