Jira - The #1 software development tool used by agile teams. Jira Software is built for every member of your software team to plan, track, and release great software.
Pivotal Tracker - Pivotal Tracker: The awesome, lightweight, agile project management tool for software teams. Get your 30-day Free Trial started today!
Redmine - Flexible project management web application
Mantis Bug Tracker - Mantis Bug Tracker is a free and open source, web-based bug tracking system.
Trac - Trac is a project management and bug/issue tracking system. Provides an interface to Subversion and an integrated wiki.
SourceForge - The Complete Open-Source and Business Software Platform.