From iDevices, the iPeople behind the iGrill, comes iShower - a battery-powered, Bluetooth-enabled, water-resistant speaker for what its makers charmingly refer to as "aqua-centric environments." The iShower can stream music from any Bluetooth-enabled Apple or Android device, apparently to an impressive range of up to 200 feet (60 meters).
The iShower can be detached from its wall mounting (in your shower is recommended) for use anywhere one might be nervous of taking a smartphone - the beach or pool, iDevices suggests. The device runs on three AA batteries for a claimed 15 hours of streaming. That's just about enough to sing your way through 125 showers. Or one pool party.
The iShower has all the playback and volume controls you'd expect from a stereo, displays the time of day, and can be installed without need of tools. There are free-standing and suspended options if wall-mounting is not convenient, and an anti-fog shower mirror is available as an extra.