Here's a collection of some of the 'classics' from way back. The graphics weren't up to much - especially by today's standards - but the game play was surprisingly addictive! The Simon game is a good flash simulation of the hugely popular memory game from Milton-Bradley.
I remember the batteries always seemed to go flat whenever you were really close to beating your high score!

Arkanoid

Frogger

Pong

Simon

Space Invaders

Tetris