If most of the open source projects for Scrum tools have ended being transformed in a limited offer that supports a main commercial product, this has not been the case for Kanban. The simplicity of the Kanban approach has allowed open source software developers to create and maintain Kanban tools based on various platforms.
Trello is a free on-line project management tool owned by Atlassian that provides a flexible and visual way to organize anything. This approach is naturally close to the visual boards used in the Scrum or Kanban approaches. As the tool as an open architecture, some extensions have been developed for a better implementation of Agile project management in Trello and provides additional features like Scrum burndown charts or the implementation of WIP limits.
Although many might tend to limit the concept of agile requirements to “user stories”, this book by Dean Leffingwell reminds us that there could be more than just a post-it on an information radiator when we talk about Agile requirements. The title of one of the initial chapters is “The Big Picture of Agile Requirements” and this book provides it, together with the small details that can help you write better user stories.