MantisBT is a popular free webbased bug tracking system. It is written in PHP works with MySQL, MS SQL, and PostgreSQL databases. MantisBT has been installed on Windows, Linux, Mac OS, OS/2, and others.
Index constantly checks hot and trending companies for their latest activity. We haven't gotten to this company yet, but if you follow it you'll be the the first to know when Mantis Bug Tracker makes some noise.