Mike Brown has written a nice (free)E-book on Innovation. Mike is the founder of the Brainzooming Group. They have developed the Brainzooming Approach to Innovation and Creativity.
In his E-book he reviews eight approaches and perspectives to help you and your team to become more innovative. You can download his free E-book here (you may need to sign up for an also free account at slide share) and enjoy the insights he offers.