Trello is a SCRUM like free online application.

http://opensourceecology.org/wiki/Trello

Trello Broke My Brain...

Trello Burndown is open source! (Burndown charts for Trello)

“Saying “always be free” doesn't create a legal obligation given a change of circumstances.” :

• http://news.ycombinator.com/item?id=4218739