Audacity is a free opensource audio editor utility which also cross platform.
Developed by The Audacity Team
Apps available for
Mac OS X
Edit MP3 Files
Edit MP3 audio files to add or remove parts using wave editor.
Cut MP3 Files
Cut one MP3 audio file to multiple small MP3 audio files.
Join MP3 Files
Join two or more MP3 audio files to a single file.
Audacity is an Open Source Product.
The Audacity Team has developed Audacity