Brainstorming is a technique that utilized a team approach to problem solving. Generally there is a group leader that is in charge of putting the group together and communicating the findings to outside people. There should be a facilitator that keeps the group focussed on the task at hand and makes sure everyone has a chance to participate. Also there should be a scribe to keep notes on what was discussed and decided.
The leader will let the other members propel the conversation. Although the leader bears ultimate responsibility for the results his or her participation must not overwhelm the other contributors. The facilitator must stay completely neutral. He or she should ask questions to stimulate discussion. The scribe can contribute to the discussion freely. Surprisingly the scribe will often not participate. The reason for this is the writing of the notes consumes the left side of the brain. However the ability to brainstorm requires engagement of the creative right side of the brain.
For best results allow ideas to flow without judgment. Once you start to judge or criticize ideas people will start to second guess themselves before speaking. Once all ideas have come out, then you can go back and eliminate those that are not feasible. Encourage ridiculous and 'impossible' ideas. Sometimes the insane ideas then lead to the optimal solution.
When developing your web site strategy you will want to form a task force for this effort. Choose people from different areas of your company. If you have a very small company, involve everyone. If you have a one person shop, ask your spouse, friend or neighbor to assist.