We've seen some good portable iPod/iPhone audio systems in our time, but Eton's Soulra is one of the more intriguing products we've come across in this category.
The unit's got an aluminum and rubberized body that the company says is splash-proof has and the speakers are sealed on the inside to provide "protection from sand, water and other outdoor elements." On top of that, the $199 Soulra incorporates not only a rechargeable lithium ion battery but a high-efficiency solar panel that allows you to trickle-charge the unit while it's outside (so long as there's ample sunlight, of course).
We got a demo of the Soulra in our offices and thought it sounded pretty good in the limited time we spent with it. Available now in black, the Soulra comes with an AC adapter and a remote (for full tech specs go here). We look forward to trying it outside by the pool and seeing how it holds up after a few cannonballs.