I don't use a unique four-stage IntelliTank™ process to think outside the box and churn out IdeaGiblets®.
I'm usually given the brief and I disappear home with a bottle of Blue Nun and a packet of Rizla returning the next day with two pages of ideas.
Admittedly, some may not be what you were expecting* but they'll be on brand, will get you coverage and I guarantee you'll like a few.
I'm used to running facilitated brainstorms, which ideally involve the client. I ran one recently with a team of high-level management from BT Global Services. The resulting ideas were used the following quarter as speaking topics for their CEO.
I've written a guide to successful brainstorming which is now used by three PR companies and a branding agency. I recently advised creative hotshop Freud Communications on ways in which to improve their creative processes.