Amazon recently made some waves when it released its new Cloud Player—a media tool that stores and plays your entire music catalog via computer or Android phone. No synching or copying required. Sick, right? Very, but the online retail giant isn't the only company streaming music from the skies. Companies like Rhapsody have been doing it for years, while new comers like mSpot and the recently introduced DropTunes have launched web and mobile applications that allow users to listen to their tunes wherever they can get an Internet connection. With cloud music services advancing and offering features like music playback, social integration, and multi-platform support—it's not only becoming the essential back-up storage plan—it's becoming the media player of today. Take a look at 5 Cloud Music Services Worth Checking Out.