Doodle Box
Really impressed with this strategy for quickly creating a number of ideas. I thought that it was especially good for making witty associations that might otherwise go begging - as a graphic designer it's useful to be able to identify a feature in one context and then present or use it in another. Perhaps more effective for illustrators where elements not normally associated with a subject are utilised, e.g. a square becoming the body of a dog or the ear of an elephant.
Setting limitations can sometimes stimulate creativity and imagination.