There are some sites online which use the konami code which lead to some interaction once the code key are pressed while the particular website is in focus on the screen.
Facebook also utilizes konami code (famous as cheat code for facebook) to produce a glare on the screen when the person tries to click or a flare when he tries to write on the facebook page (also called magic circles).
The konami code is:
up up down down left right left right b a enter (or return)
The Konami Code, known in Japan as the Konami Command (コナミコマンド Konami Komando), is a cheat code that appears in many Konami video games, although the code also appears in some non-Konami games.
It has become very popular to implement this code within your website often using jQuery to listen for the keystrokes.
Some of the websites using the konami code and jQuery are:
You can get a list of sites using it here: http://konamicodesites.com/ and http://en.wikipedia.org/wiki/List_of_Konami_code_websites .