In a bunch of games that Kazumi Totaka has composed music for there is a hidden song with 19 notes.
Games that these are in are (taken from Wikipedia):
"X The song has been found in the games soundtrack.
Mario Paint The song will play after on the Title Screen if you click the Letter "O" in "MARIO" on the title screen.
Animal Crossing series To hear the song in Animal Crossing or Animal Crossing: Wild World, enter the request "K.K. Song" from K.K. Slider between 8pm and midnight on Saturday nights (in the Wild World version, K.K. Song is not limited to a request-only selection. K.K. Slider is capable of selecting the song randomly). You will also receive an aircheck to listen to in your house. It can also be found in the N64 version of Animal Crossing, also known as Animal Forest.
Link's Awakening To hear the song in Link's Awakening, go to Richard's Villa (the house with several frogs hopping about), head inside, and wait for two and a half minutes. In the Japanese version of Link's Awakening DX, another version of the song can be heard at the file selection screen by entering the name "Totakeke" (とたけけ) to start a new file, in the same way the name "ZELDA" can be entered to hear an arrangement of the game's theme music. Other samples of the song have been found in the game's coding but not in the actual gameplay.
Super Mario Land 2 To find Totaka's Song, lose all of your lives to see the Game Over screen. Wait at this screen for two and a half minutes and the song will play.
Virtual Boy Wario Land To hear the song in this game, defeat the final boss, and after the credits finish, wait at the "END" screen for a short while.
Yoshi's Story To hear Totaka's Song in this game, select Trial Mode from the main menu, and wait at the level selection screen.
Pikmin 2 To hear the song in this game, go to a uncompleted cave level and wait at the Treasures salvaged screen.
Luigi's Mansion To hear the song in this game, go to the controller configuration screen in the training room and wait.
Yoshi's Touch & Go To hear the song you must find a level which has winds that blow away the clouds that you draw. The area will not last long enough to let the music loop to Totaka's Song, so you must pause the game in this area to hear it."
Games that the song have not YET appeared/found in are Wave Race 64 and Wii Sports, So START LOOKING!
Sample of the song --- http://youtube.com/watch?v=EfXSa0m_ryc just keep watching until you hear it and hey! you never know, it could be played backwords, slower, faster but it will probably sound in a different tune.
I was actually looking for my own glitches when I found this. I WAS going to rent the gamecube and use action replay for gamecube with it since I had it but I didn't want to waste my parents money. I'm just happy I found something that I was the first to find.