Jira may be extremely sluggish and require a large amount of memory on the client side.
Stack Overflow - Community-based Q&A part of the Stack Exchange platform.
Asana - Asana project management is an effort to re-imagine how we work together, through modern productivity software. Fast and versatile, Asana helps individuals and groups get more done.
The Answer Bank - The Answer Bank is the UK’s leading question-and-answer site.
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.
Askalot - Askalot is a next generation CQA (Community Question and Answer) system.
Wrike - Wrike is a flexible, scalable, and easy-to-use collaborative work management software that helps high-performance teams organize and accomplish their work. Try it now.