I agree with most of Nick Currie's [AKA Momus] observations on brainstorming (a common decision making technique). I have facilitated or contributed to lots of brainstorming. Although they are creative and feel like fun, most brainstorming sessions result in a hodgepodge of ideas that no one really cares about except the person with the idea.
Nick believes that traditional brainstorming has been made obsolete by digitally-enabled role-playing games, avatars, and other ways to use masks to reveal ourselves. I have successfully used simple role-playing to make the point that the players in a process have different points-of-view. I have not yet tried actual masks.
Check it out.
Update: see my earlier post on Martin Leith's large and interesting collection of idea generation methods. Link