Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Community Questions for Confluence - Keep questions and answers in one place with an engaging, community-driven Q&A discussion forum, powered by Confluence
KanbanFlow - KanbanFlow is a Lean project management tool allowing real-time collaboration between team members. Supports the Pomodoro technique for time tracking.
Question2Answer - A Q&A site helps an online community to share knowledge.
Meistertask - MeisterTask is an intuitive task management and collaboration tool.
Stack Overflow for Teams - Everything you love about Stack Overflow in a private space.