I've occasionally brought a set of computer speakers into the bathroom with me and plugged my mp3 player into them. While this is nice, it's a pain in the behind and I'm always nervous about splashing them and shorting something out.
I decided what was needed was a waterproof enclosure for the speakers and the mp3 player. I actually built this project as a Christmas gift for my girlfriend, as she loves singing in the shower even more than I do and is actually good at it. I did my best to make this look nice and professional, rather than my usual cobbled together mess of wires and circuit boards.
Just a quick warning, I don't know how waterproof this really is. I suspect it'll be safe to splash it every now and then, but I wouldn't recommend actually using it IN the shower. Nearby should be good enough.
Here's a little youtube video I cooked up for this instructable. Some of the shots are pretty dark, but I think I've figured out how to avoid that in the future. On the plus side, It does have me singing in the shower!
***UPDATE 5/5/10: If you build your own set of waterproof speaks, post some pictures in the comments and I'll send you a patch!***