After you get the elemental sprite 'Thermite', go to the forbidden forest and find the house with a giant rock blocking it's entrance. Use Thermite's ability to shoot lava bombs at the door, and you can now enter the home. Near the entrance to the left, there is a small radio. Play the radio to hear a rock version of Banjo-Kazooie's main theme.
Kameo started out as a Gamecube game, and was meant to be a launch title. During the development, Microsoft bought Rare, and the title was moved over to the Xbox. After many delays, the title was moved to the Xbox 360 as an exclusive.