Brilliant resource: The Oblique Strategies
One of the most idiosyncratic brainstorm tools is the “Oblique Strategy” deck created by musician Brian Eno and artist Peter Schmidt. Now mostly lost to modern brainstorming techniques, I have found the deck to be surprisingly useful with entrepreneurs, precisely because it is so unexpected. An online version that shows one card at a time can be found at www.oblicard.com. It does not work for many people, not only because the messages are often couched to help design new music. If you are really stuck, give it a try; prepare to be surprised.