SourceForge - The Complete Open-Source and Business Software Platform.
jtrac - JTrac is an open source and highly customizable issue-tracking web-application written in Java.
openDesktop.org - The website openDesktop.
Bugify - Bugify is a simple PHP issue tracker, designed to offer powerful bug tracking capabilities in an easy to use system.
OSOR - OSOR is the Open Source Observatory, a project to provide a framework for developing and executing autonomous observations.
16bugs - 16bugs is an all-in-one bug tracking software that makes it easier for you to manage all sorts of bugs in performance with the simple interface; ultimately, you will be more productive for sure.