Every year for the last 6 years I've supported http://www.lbeh.org/
Its an effort to buy plane tickets for enlisted men and women to allow them to fly home for the holidays. Its an all volunteer's effort last year they spent 96% of what was donated on the troops.
(2.5 % of the take went to PayPal fees.)
This is the one and only time of the year I'll post a request on the blog.