Work Breakdown Structures are a useful tool to help you to identify the packages of work that will need to be done in the course of a project. They are usually created as a hierarchical list of tasks presented as a Tree Diagram, or as an indented list. Both of these approaches are very “rational” and sometimes people working on projects prefer a more creative way of working. Mind Maps are another, perhaps more creative, approach.
Mind Maps can be a great way to get teams engaged in working out what needs to be done, without getting bogged down in tools such as MS Project and Gantt Charts.
A simple, free MindMapping tool is Freemind. You can export the outputs into MS Excel or MS Project later, if you need to.
More on Project Management.