Hm, jingle, that's the first time I've heard it called that. Whenever I think of jingle I think of a 60's black & white commercial for laundry detergent. 😛
Of course I think it would be super-cool to replace the modern start-up chime with the old Mac Plus chime. 😀 Edit: Ooh, or better yet, the Hawaiian Death Chimes! Watch any Mac aficionado do a double-take and watch their heart jump into their throat. 😀
And then, there's always the mute key... if you mute your system before shutting down/restarting, it will normally apply to the startup chime too. But that's kind of a pain if you use sound often...