Here's a tip for adding music or sound effects to just about anything. The concept here is so simple, that it's really more of a public service announcement than a How To.
The first ingredient is an MP3 player. As of this year, MP3 players have become so cheap that you can really have fun with them in a way you couldn't before. A 2GB MP3 player these days can be found for as little as $20.
Click here to see a video version of this tutorial.
With your new miniature sound system, you could add the "Thriller" soundtrack to your kid's Halloween candy basket or a costume. Use it for playing calming music during yoga or meditation. Heck, at this price, you could just strap it to your bike and ride and take music with you everywhere without worrying too much about it getting ripped off. Be creative. Have fun.