Mac: We love Sonora, the great iTunes-alternative music player with awesome queueing features and a fantastic interface. Version 2.0 advances those features, and lowers the price from $10 to free.
In addition to better queueing support, with a simple (and re-arrangeable view) at the bottom of the player, the latest version of Sonora allows you to save any queue as a mix. Sonora 2.0 also adds additional views and sorting options and social media sharing.
While you used to get Sonora on the Mac App Store for $10, you can just download the latest version (a very stable beta) for free from the app's web site. The sad news is that Sonora is no longer in active development, but the source code has been made available on Github so any ambitious developer can continue work on this great app. Even though future versions aren't guaranteed, 2.0's still a wonderful alternative to iTunes — especially considering it can import its content and no longer costs you anything at all to use.