These speaker systems can extend just about any device you intend to play music off of. This includes iPods and other MP3 players, iPhones and other cell phones, laptops and netbooks, iPads, etc etc. Basically, if your device has a place to plug in headphones- these ultra-portable mini speakers can provide a louder, crisper sound.
There are quite a few little systems popping up like this, most with pretty good ratings. It ultimately comes down to which one you like the looks of better. The gold medal (iHome iHM60GT) and silver medal (X-Mini II) winners are about the same size, and have better ratings and more reviews than the competition. The bronze medal winner (iLuv iSP110BLK) is a bit larger, accommodating two speakers and an inner compartment to protect your mp3 player or cell phone. Whichever one you choose, you’ll be amazed at the sound these small speakers can put out!