Windows only: Advanced audio editing tool Free Audio Editor handles your music and sound editing with an attractive, streamlined, and easy-to-use interface.
The application handles common audio formats (from MP3 and WMA to WAV and OGG) and boasts a rich set of features: Batch processing, recording, CD ripping/burning, and text-to-speech make this application worth a look for anybody that needs to do some quick audio editing without paying for a commercial application.
Of course, no audio editing post would be complete without mentioning the also-free, cross-platform, and open-source Audacity, useful for anything from removing vocals to creating ringtones from any MP3.
Free Audio Editor is a free download for Windows only.
Free Audio Editor [via Life Rocks 2.0]