Some of the games we did for the MN Pony Meet:
Guess how many combs are in a jar (or McDonald's ponies or whatever)
Everyone gets a pony comb/paper clip/clothespin/safety pin, and if someone says a certain word (like Pony) the person who catches them gets to take it away. The person with the most at the end of the day gets a prize.
Put a pony in a bag ( like a black pillowcase) that you can't see through and see if you can guess it by feel alone. (definitely doing this at the MN Meet this summer!)
Tape the name of a pony to everyone's back and have them ask yes/no questions to find out who they are. I actually got stumped by my own trick question last year! (Glory/Rarity- they're very confusing!)
Match the furniture to the playset it belongs to.
Those are a few- I'll be watching this site to get more ideas!