Andy Eklund is great – brainstorming techniques
Lotus Blossom: http://www.andyeklund.com/brainstorm-technique-lotus-blossom/
What is a big idea? http://www.andyeklund.com/what-is-a-big-idea/
New Point of View: http://www.andyeklund.com/creative-brainstorm-technique-new-point-of-view/
SCAMPER: http://www.andyeklund.com/brainstorm-technique-scamper-1/

Eno’s Oblique Strategies cards online: http://oblicard.com/