1. Don't buy Apple RAM. This should be stenciled on every Mac box, printed on UPS driver caps, and possibly placed on street stickers outside the Apple Stores (I kid! Don't sue me). I recently priced a 512 MB upgrade for a vintage G4 iBook, and while I would have liked the convenience of the Apple Store for quick pickup, I could not possibly justify the 300+% markup over crucial.com's or OWC's price for the exact same part ($150 vs. $38). I doubt that an educated-customer avoidance of Apple memory, either BTO or upgrades, will make much difference to pricing policies, but this situation is so insanely out of whack that something has got to give.
Update: Several readers have pointed out that you should hold onto your factory RAM in case you need to troubleshoot problems down the road, a good suggestion -- Apple support or Genius Bar techs will often ask you to return your machine to as-shipped condition. If you want to cross-check that you're getting the same manufacturer as Apple uses, you can always compare RAM prices and part specs in a jiffy at dealram.com. Reader JC did a quick survey of manufacturer markups on RAM and suggests that Apple's pricing may not be so far out of line when compared to other high-end computer vendors like Sony; still, I stand by my statement that buying Apple RAM is too expensive.
2. Make a shareware gift basket. You've got the massive downloads folder and the experience with your favorite Mac programs; why not leverage that? Burn a CD full of your top shareware apps, or register a couple of them in your buddy's name. Nothing says "I care" like software.
3. Give the gift of bookmarks. Your experience as a Mac veteran has populated your browser bookmarks with a zillion helpful sites; export them and send them on over! If you need a starter list: macfixit, macintouch, macworld, dealmac, macosxhints, versiontracker, iusethis, and of course our humble little blog.
4. Provide a personal support gift certificate. An email that says "call me anytime" might give too much license for midnight pleas for help -- maybe a stylized one-sheet saying "This certificate good for three hours of handholding, gentle instruction, wireless troubleshooting & general Mac advice" will set the ground rules.
5. Deliver the Kool-Aid. One of the hardest transitions for recovering Windows users to make when adjusting to the Macintosh Way is the attitude: expecting things to "just work" instead of having to tweak registry settings and swap out DLLs, being willing to cooperate with your computer instead of fighting it all the way. Sit with your buddy and watch them work for a bit; if you notice points of friction, try to lubricate. Remind them they can still right-click, allow them to plug in a printer and not go searching for drivers. See the light in their eyes return.