Audacity - Audacity is a free and open-source audio production software suite that includes a surprising array of editing tools and recording systems.
WaveShop - Open source audio editor
Spek - Spek helps to analyse your audio files by showing their spectrogram.
TwistedWave - TwistedWave is one of the unique audio editors that allow you to edit your music file online without any installation.
SoX - Sound eXchange is a command line utility that can convert various formats of computer audio files...
Radium - Radium is a music editor with a new type of interface.