With this gadget play a pong clone on the Windows Sidebar. It's (very) difficult, but possible to win according to the author.

 
This gadget is a nice and simple blackjack game.

 
This gadget is a  clone of Atari's Asteroids game.

Get three X's in a row (horizontal, vertical, or diagonal) before the computer gets three O's in a row, it isn’t easy.

 
You are bored?  Made pop some bubbles with this gadget! You can change the color of the bubble wrap to fit your desktop.