In April 1989, Nintendo released the Game Boy. How time flies when you're having fun, because it's now April 2009, so a rousing chorus of "Happy Birthday" is in order for the venerable little machine.
Having sold around 120 million units in its 14-year production run (that's including sales of the Game Boy Color), the Game Boy gave way to the Game Boy Advance, which begot the Nintendo DS. Which isn't anywhere near as great because it's not called the Game Boy DS.
Being near-indestructible, easy to carry around and with plenty of battery life, the Game Boy saw off a number of competitors in its lifetime, from Atari's Lynx to Sega's Game Gear, before finally being retired in 2003.
It brought us portable gaming. It brought us Tetris. It brought us Pokemon. So drink up, old man, and enjoy your special month.