When my brother pinned on silver oak leaves, I got him one of these:
http://www.ebay.com/itm/Barrack-Room-Ballads-and-other-verses-Rudyard-Kipling-1892-First-Edition-/390427996513
It is a gift of particular relevance for those who serve in the combat arms, or have spent time in Afghanistan.
These are good suggestions and something to think about. Thanks!