Peace,
USO is by far the best place. You can designate what you wish to have the funds used for if you wish and you can also get a tax write off if you so request. A fellow FReeper is going to post a thread here requesting folks to donate to the Korean chapter of the USO to get calling cards to the guys on the Korean DMZ. I'm a civilian here in Korea and can tell you first hand that these guys have it pretty rough up north and they will certainly appreciate it if you'd like more info, just say so.
Name is Ray and I'm in Seoul, Korea.
Peace, If you reply, please do so by private reply. Thanks