First, a little history lesson: This is a cheat code used in many classic videogames, specifically games made by Konami. It was first used in a game called Gradius, but it was made famous by the game Contra for the NES. This code, if entered in at the title screen, gave the player 30 lives (opposed to the 3 that you normally start out with). This code became well known and popular enough that different versions of it have been used in many games since. I remember using a similar code in the game Teenage Mutant Ninja Turtles III: The Manhattan Project. If you entered Up, Up, Down, Down, Left, Right, Left, Right, A, B, (Select if you want to play 2 players), Start on the title screen and after choosing your character, a new screen would appear where you could change the options of the game. You could change the level (or scene) you started on, the difficulty (easy or normal), and how many lives you started with (3, 5, or 7). On the same screen was a sound test thing where you could listen to all of the music tracks in the game.
More recently, I have found this code to be used on some websites. Just last week, the Konami code could be used when visiting ESPN.com to make rainbows and unicorns appear, but this was quickly removed. A list of websites that use the Konami code for something can be found here: http://konamicodesites.com/ (You need to enter the code to access the site.) Some are strange, some are "meh", but others are neat. My favorites are Facebook, Specced for Awesome (zombies), Paul Irish (I think this is the same type of thing that was on the ESPN website), and Patrick A. Carrell Design.
