ITunes

iTunes is "a media player and media library application developed by Apple Inc. It is used to play, download, and organize digital, audio and video on personal computers running the OS X operating system and the iOS-based iPod, iPhone, and iPad devices, with editions also released for Microsoft Windows." iTunes isn't often the choice media player for most people, who normally prefer other media players such as Foobar2000, but some there are some fans of it, including some people on /mu/. If you are a Windows user, it is recommended to only keep it around for syncing with your iPod/iPhone, as iTunes can be quite the resource hog for non-OS X users. It can be downloaded from Apple's website.