My wife has the same problem. A couple of decades ago she bought me an air compressor and for a couple of years she would give me new air tools.
If his current compressor is in good shape, you can always buy him a BIGGER impact wrench, or a NEW sand blasting booth, or my next purchase, a rivet gun and bucking bars.
Although I like the RotoZip idea too. Just don't ask for a 'spiral saw' at HD, the old geezer had no idea what I was talking about.
Those 1:18 diecast models that you see on Ebay and AirstreamDreams make a nice conversation piece for us old kids.
A new hat might also be appropriate for the occasion.
XM radio! We love it for travel--got all the music we like in the deadest reception areas while on the road-and we don't carry along nearly as many CD's as we used to. (Of course, that goes without saying that we are not nearly as techy as all of you that can load thousands of tunes on a credit-card sized whatever! XM has our vote and you can even get a portable unit to haul to the beach or mountain top or whatever off the road place kind of ambiance you seek out. Janet, we think you ought to wrap up XM for Gary's big 5-0!