Actually, I've found that Quartz Desktop works pretty well for that kind of think. It just sits in your menu-bar and has options for stop/start and can even allow you to edit the composition. It's free.
(It's a good idea to have the Leopard developer tools installed. Look on the OS install disk that came with your computer.)
Actually, this is one that I scrapped together and I think looks pretty spiffy. (See attachment).
(OK, nevermind; since there's a ridiculously low file size limit, I guess I'll have to upload it to somewhere else. I'll post the link here once I've done that.)
