SimplyVibe SV-X6U1-White Rechargeable Portable Multifunctional Speaker and MP3 & FM Player (works w/ iPod, iPad, iPhone, Android Devices) - Accepts USB Drives and SD Cards
Works great. The batteries last long and the sound is (as other people have pointed out) pretty good for such small speakers (But it doesn't seem to be stereo). You have to get used to the menu system (e.g. how to move from folder to folder...), and the lack of documentation. Besides that, I think it's pretty decent considering you can use SDHC as well as USB memory sticks.