If you wanted to pick him up something he would probably never buy for himself, but darn rippin handy. I've been loving my little Truma LevelCheck
It's an ultrasound propane level detector. And it really works!! No more weighing or having to pour hot water over the stick on gauge. They want $70 through their website, but I picked up mine, new, on ebay for $52 including shipping.
It's definitely not really a necessity or terribly practical, but boy is it fun to play with.
It's been really interesting being able to track actual daily consumption by the different systems in my rig.