Smart toys and games for gifted children
It will depend on the age of your child but here are the ones I thought of and the latter are from a google search:
Chess and other strategy type games.
Word puzzles. Books or other word games like Boggle etc.
Apples to Apples
Mad Gab Game
Science lab kits
What are your ideas?
Also Non Fiction books like books on how the body works, planets, history, things like that.