While it's packaged as a way to talk your kids out of getting high via a WWJD-type bracelet (LAME!), the Sound Advice Project nevertheless makes a cool bracelet of any sound's waveform for $US18.
Not that I'm trashing the whole "talk to you kids, keep them off drugs" message behind this project. They will still get your money when all is said and done. But this visualisation of sound has wider applications. Especially if you're capable of automagically hearing a sound by looking at its waveform like I am. And the price is right. [Sound Advice Project via BBG]