Cog: open source audio player
Lots of people bemoan the fact that iTunes doesn't offer support for some of the more obscure audio formats (most notably Ogg Vorbis). Most people who care about Ogg support tend to be fans of Open Source software, and probably aren't thrilled with using iTunes anyway. Luckily for them there is Cog. It is an open source audio player for OS X that supports a boatload of audio formats, though its feature list isn't quite as long as iTunes.
I suppose you get what you pay for, oh wait, iTunes is free as well (though decidedly closed source).
[via HiFi Blog]