I'll second Eric on Thinkertoys. When I started using it I had the fortune of a seasoned manager who was planning to buy out his company in the class, and he liked the book a lot and told the class that it saved his company a lot of money. This gave the book credibility. Some students will tend to find some of it a bit too far out. That is one reason I suggest giving students a range of possible exercises (chapters) to do. Further, although the book makes this clear, it's important to link each exercise to a particular challenge that the user is trying to overcome.
I haven't used Business Model Generation by Alexander Osterwalder and Yves Pigneur. It's a more focused creativity book - focused on business models, of course, and it IS a creativity book despite the generic title. I might use it in the Fall - haven't decided yet. Certainly the topic of business models tends to give students trouble.
Alex Stewart, Ph.D.
Coleman Foundation Chair in Entrepreneurship
Marquette University
Milwaukee, WI 53201-1881
Office: 414 288-7188