Most retro sega games (mostly sonic): (http://www.youtube.com/watch?v=BHcJwaFDok4)
All werehog intros to sonic unleased: (http://www.youtube.com/watch?v=Kp1zoN8HsEw)
(http://www.youtube.com/watch?v=4fE9d9dvIu0)
(I only could find two :p)
I like the gamecube bootup jingle. Did you know if you hold down the z button on the gamecube controller while it's booting up, it will play a different jingle.
Link's awakening and zelda nes opening music iamong some of my favorite.