How about cooking?

Lots of fun things to try, lots to learn (nutrition and such), can get very creative, plenty of fun tools (flaming torches to melt sugar on creme brulee!), dishes and cooking utensils to buy and learn to use, tons of ideas on the internet, forums, etc.

Maybe he could do vegetarian one day, Italian the next, Norweigan the next, a Cuban day, and so on.

He gets a hobby, you get someone cooking for you!