The ten Faces of Innovation by Tom Kelly of IDEO describes 10 roles usually found in innovative groups. Now, this isn't one of my usually book summary/reviews. Mainly because I do not have to. Someone did all the hard work up front. Read the first chapter of the book at Fast Company: http://www.fastcompany.com/magazine/99/faces-of-innovation.html and get a more detailed list of the ten roles at the book website: http://www.tenfacesofinnovation.com/tenfaces/index.htm
And then go read the book :)
It is well written, with good stories, and it felt reinvigorating and got me thinking about all the things I know we should do that we don't, and gave me some ideas for getting better.