Canabalt
Impressively entertaining game despite how easy it is. Simply use the space bar to jump over obstacles.
Codes for your website:
<div style="text-align: center; font-family: arial, sans-serif; font-size: 12px; width: 70px;">
Canabalt<a href="http://www.groovyjava.com/games/canabalt/" target="_blank"">
<img src="http://www.groovyjava.com/games/canabalt/canabalt.gif" title="Play this game" style="display: block; border: 0;">
Flash Game</a></div>