Chris Sells, Program Manager at Microsoft refers to MindJet‘s MindManager software while blogging about vital PM skills.
“My preferred technique for building consensus is what I’ll call "the big mess." The idea is you get the team (or a representative sample of the team) into a room and you ask the leading questions, e.g. What are we trying to accomplish? How do we get there? Who does what? How does that fit into the bigger picture? How do we involve folks outside the team? I call this technique "the big mess," because that’s how it starts and it only gets better through discussion and debate, led by the PM. One nice thing is that it’s usually a lot faster than holing yourself in an office, because you don’t have to make all of the planning decisions yourself (sometimes you don’t make *any* planning decisions), although you better be a fast hand at keeping track of the team consensus as it builds and playing it back periodically to make sure everyone’s staying in sync (Oliver Sharp turned me onto MindJet‘s MindManager software for this task)."