Nintendo Game Boy - The ORIGINAL version. Ah, hours of playing Tetris, Boxcel, and The Little Mermaid. And borrowing Super Mario Brother's Six Golden Coins from the neighbors! So much fun! Still got it dont think it works. My gameboy pocket works though
Balloon Rockets - I've done this in several science camps I've conducted. Kids have fun with it. But, when the balloon deflates it may fall off the straw because it's surface area changes - another good thing to show and explain to kids.