I'm sure you're looking for something aviation related, but I'm sure something practical/entertaining would be appreciated as well. Subscription to Netflix, gift certificate (movie buff? Best Buy. Car Guy? Napa/Checkers/Pep Boys), a nice bottle of scotch/whiskey/vodka/moonshine/turpentine. All of this would be in the 25 - 100 dollar range.
A nice card with a family photo, and a little cash, would go over well with any new aviator as well.