One of my favorite music apps this past year has been Ex.fm.  In its first iteration, it was a Chrome extension that let you grab and share MP3s from anywhere you surfed the web.  They deftly expanded the experience into a very slick social music player (here’s my profile).  Today, the team just launched their iPhone app - and of course, it rules.  These guys are some of the best programmers in the business and it shows - the app is fast and intuitive and is full of useful features yet unburdened by fluff.  Grab it now from the iTunes app store. Android version coming soon!