Like others have said, he won't be able to take much. He'll have a list of what he needs, and maybe you can help him get his list together. Other than that, care packages may not be allowed (and he might be lightly punished--pushups and all that--if he gets one). Letters are always welcome, though! The phone/address book is a great idea, and also vitamins aren't bad, if he can have them. He'll be much more flexible after he leaves boot camp, so feel free to send him a gift after graduation or care packages once he gets to tech school (it's still nice to be remembered after basic)!