Out of the mess that is the music industry’s battle against online piracy have emerged two basic legitimate business models for downloading music: the per-song or per-album charge, and the rent-a-music-library-by-the-month system. So which is better, and how do you get the best value for your music dollar? The answer may be surprising. “With a few well-placed strategies, you can leverage the subscription model to make your days and nights more musical — at home, at the office, or on the road.”