From Tatsuaki Kuroda:
S8Tunes is a handy tool that can help you listen to your favorite songs. You can listen to your favorite songs anytime. Apart from that, s8Tunes comes with tempo, cent, and key controls and lets you easily edit playback speed or pitch of the songs. The edited songs can be saved in WAV (by default) or MP3 (by pasting an additional file into s8Tunes folder) formats.