Audition was one of the first serious projects that I open-sourced. In 2002 I built a site for a friend's band, and out of that site and its tools came Audition. For awhile I sold the software, but when it became clear I didn't have time or energy enough to work on it, I open-sourced it. Here are some screenshots:
Audition requires a newish, stable version of PHP 4.x, and MySQL 3.23 or greater. GD Library extensions are required for image thumbnailing.
I haven't touched Audition in about a decade, but you can still find it on Google Code.