Six Thinking Hats (opens in new tab)

We've tried this at work one time during one of our iteration retrospectives. It took a while for the meeting organizer to explain how it worked, and took a while for people to adjust to it. The consensus at the next meeting was to just go back to "What worked", "What didn't", and "Action items". It was simple, easy to understand, and captured the points we wanted to.

I took a course with Edward de Bono himself teaching it in the nineties. He sat with an overhead projector next to him and kept sketching all these little nice diagrams. It can help you classify the various effects of a decision. On the creative side some techniques worked for me like introducing random words and so on.