I've always been partial to elaborate outdoor speaker systems. Well hidden, they make it seem as if the music is just coming from the atmosphere. It also makes your yard feel a bit like Disneyland. My Uncle Tommy had one of these in his yard, except he always played Shania Twain through it, which never felt right. I'm thinking more along the lines of Bjork.
Either way, a rock seems as good a disguise as any. Who looks at a rock? The speakers on these ones from Audio Unlimited can grab a 900 MHz wireless signal from up to 150 feet away. [Via Nexus404]
[$149.99, Cables Unlimited]