ClockingIT is a complete multi-user Web based project management solution with a focus on handling large amounts of tasks during software development. It features an unlimited number of projects and tasks, tagging, email notifications, RSS and iCal feeds, time tracking, file uploads, reports, forums, and issue tracking.
Devalot is a social networking application centered around software projects. It connects the user community with the development community and encourages participation and communication. It includes all the features you've come to expect in modern Web-based applications such as tagging, comments, and a wiki, as well as features you'd expect in project tracking software such as ticketing. It has features similar to some of those found in Trac, Collaboa, GForge, Mephisto, and Typo.
Redmine is a flexible project management and issue tracking Web application. It supports multiple projects, flexible role based access control, Gantt charts and calendars, news, document, and file management, feeds and email notifications, per-project wikis and forums, time tracking, custom fields for issues, time entries, projects, and users, SCM integration (SVN, CVS, Git, Mercurial, Bazaar, and Darcs), issue creation via email, multiple LDAP authentication support, user self-registration support, multi-language support, and multiple database support.