My niece (5) learned all about magnets with those, she was SO impressed that they stuck on things, we had to run all over the house testing out every semi-shiny thing. She learned that they DO stick to the fridge, NOT the dog. (arf!) They DO stick to the lamp, NOT the piano. She was hilarious.
Then she stuck one to her grandaddy's gunsafe, which my mother can't STAND anyway, so we piled 'em all on before he came home. All the girls in the house were quite thrilled, and mom was pretty smug. Yay ponies! Bravely blocking the way to my dad's man-toys! Dad even cracked a smile.
My niece DOES think ponies are magical now, in real life even. Heh.
-elph