The Free Software Foundation has started a new campaign to convince people to support Ogg Vorbis with PlayOgg.org. Other formats (such as MP3, AAC, and many others) are patent-encumbered or only available with proprietary software. You shouldn’t have to lose your freedom to control your computer just to play audio and video.
Long-time readers of Digital Citizen know that I host and steer people to multimedia encoded in free formats (Ogg Vorbis for general-purpose audio, FLAC for archival-quality audio, Speex for compressed versions of human speech, and Theora for video). I also work with others (such as News from Neptune) to help them host their media in free formats.
There are a number of programs for various operating systems to play all of these kinds of files. The audio files can be played with portable digital audio players too. So you don’t have to give up portability to keep your freedom when you’re on the road. The FSF has some instructions on acquiring and installing VideoLAN Client, a popular all-purpose media player and media sharing program.
More places you can go to get audio in Ogg Vorbis format (and licensed to share):