This classic book: "A Technique for Producing Ideas"

http://www.amazon.com/Technique-Producing-Advertising-Classi...

is short and sweet.

Bascially,

1. ideas are novel combinations

2. immerse yourself in information from many disciplines

3. think of combinations

4. Go away from it -- do something else

5. An idea comes to you

6. refine it

You might find this book useful: "A Technique for Producing Ideas", by James Young. Exceedingly short, simple, meant for advertising, but helpful for any industry.

http://www.amazon.com/Technique-Producing-Advertising-Classi...