The ZonePlayer S5 shrinks the Sonos streaming music experience down to a compact single-speaker system with great sound, which you can control from any iPhone or iPod Touch.
The Livespeakr is a good option for iPod Touch and iPhone owners who want a travel-friendly entertainment system, but the speakers don't have much use beyond that.
The Altec Lansing inMotion Classic offers a stylish way play your iPod or iPhone around your home. It sounds remarkable for its size, but it lacks the low-end oomph of a larger system.