Analogy brainstorming

http://www.atkinsglobal.com/en-gb/angles/all-angles/how-to-run-a-brainstorm-by-analogy-session
Metaphors and Analogies
http://www.andyeklund.com/metaphors/
http://www.iaf-methods.org/node/5084
http://www.brainstorming.co.uk/tutorials/analogytutorial.html