Affinity Diagrams to Make Sense of Ideas

Affinity Diagrams are used to visually organize ideas into logical groups for review and analysis. The PMBOK Guide, Fourth Edition lists Affinity Diagrams as a Group Creativity Technique for Collect Requirements process, and as an Additional Quality Planning Tool for Plan Quality process. Here's a good article that explains Affinity Diagrams:

Using Affinity Diagrams to make sense from Brainstorming