I created this section to answer questions about Bugzilla competitors and variants, then found a wonderful site which covers an awful lot of what I wanted to discuss. Rather than quote it in its entirety, I'll simply refer you here: http://linas.org/linux/pm.html

Red Hat's old fork of Bugzilla which was based on version 2.8 is now obsolete. The newest version in use is based on version 2.17.1 and is in the process of being integrated into the main Bugzilla source tree. The back-end is modified to work with PostgreSQL instead of MySQL and they have custom templates to get their desired look and feel, but other than that it is Bugzilla 2.17.1. Dave Lawrence of Red Hat put forth a great deal of effort to make sure that the changes he made could be integrated back into the main tree. Bug 98304 exists to track this integration. URL: http://bugzilla.redhat.com/bugzilla/ This section last updated 24 Dec 2002

Fenris was a fork from Bugzilla made by Loki Games; when Loki went into receivership, it died. While Loki's other code lives on, its custodians recommend Bugzilla for future bug-tracker deployments. This section last updated 27 Jul 2002

Issuezilla was another fork from Bugzilla, made by collab.net and hosted at tigris.org. It is also dead; the primary focus of bug-tracking at tigris.org is their Java-based bug-tracker, . This section last updated 27 Jul 2002

Scarab is a new open source bug-tracking system built using Java Servlet technology. It is currently at version 1.0 beta 13. URL: http://scarab.tigris.org This section last updated 18 Jan 2003

Although Perforce isn't really a bug tracker, it can be used as such through the jobs functionality. URL: http://www.perforce.com/perforce/technotes/note052.html This section last updated 27 Jul 2002

SourceForge is a way of coordinating geographically distributed free software and open source projects over the Internet. It has a built-in bug tracker, but it's not highly thought of. URL: http://www.sourceforge.net This section last updated 27 Jul 2002