Apple Store - Under the terms of the Apple Federal Employee Purchase Program, employees of the Federal Government are entitled to discounted prices at both brick and mortar Apple retail and the online Apple Store.
Sugar Games - 20% discount on Rainbow Web for Mac (demo available). "The creation of the Mac-version of Rainbow Web was a real challenge to us, but the result is worth our efforts. While porting the game, we even became Macintosh fans ourselves! And Mac User Groups consist of computer enthusiasts who love their Macs. That is the reason why we offer a special discount on Rainbow Web for Mac."
Microsoft - Probably two of the best programs for military members to take advantage of are Microsoft's Home Use Program and Employee Purchase Program. Both are basically intended to provide employees of Microsoft's biggest customers (like DoD) to be able to affordably acquire software that will let them continue work from home. Under HUP you can get a copy of Mac Office for the cost of shipping (a great incentive for new switchers worried about losing their Windows copy) and the EPP offers most of Microsoft's products at significant discounts (including Windows and even XBox games). In order to login to these sites you will need to get an official Program Code for your organization from your computer support staff.