Here's a low tech, no cost way of documenting your brain storming. I've been using this method ever since we were doing some brainstorming in one of my group meetings and we needed some large sheets of paper. We didn't have any so we just used the paper towels found in washrooms. It's free and it comes on a long roll so you are not limited to the amount of brain storming ideas you can come up. In addition, it rolls up into a nice little form to place into your bag. Try it sometime, just don't take the whole roll!