bcr beats is a beat slicer that lets you cut up and play with an audio sample: you can trigger slices and loops with MIDI or the mouse and keyboard, set pan, volume, and sample rate values, and generally have lots of fun. The interface is based on the Behringer BCR2000 MIDI controller, which means lots of knobs. It can be used with or without a controller.
Mychoonz is an MP3 player implemented in AJAX. It allows you to listen and organize your music within your browser, anywhere, anytime, as long as you've got an Internet connection. The idea is similar to projects such as Ampache or Mp3Act, but it focuses more on user interface rather than features.
Decibel is a GTK+ audio player designed for GNU/Linux. It aims at being very straightforward to use by means of a very clean and user-friendly interface. It aims also at being a real audio player and, as such, it does not include features that are not meant to be part of an audio player.
xwax allows DJs and turntablists to playback digital audio files controlled using normal turntables via timecoded vinyl. It handles needle drops, pitch changes, scratching, spinbacks, and rewinds, making it a capable tool for beat-mixing and scratch-mixing. It focuses on an accurate vinyl feel that is efficient, stable, and fast.