One of the best things I've bought and never expected how useful it would be was a battery powered reciprocating saw and got a good pruning blade for trimming trees. I'd say even the Hart brand from Walmart is good enough.
Browning game cameras are a good choice if you want to go that way.
If they are a rancher/have cattle, subscribe to to Livestock Weekly for them.
A fruit tree or something from Womacks Nursery.
Look up some of the book threads here on the outdoors board for book ideas.