A successful company has employees who are able to effectively brainstorm - to think out of the box in order to creatively solve problems. Overly rigid corporate environments are often restrictive and not conducive for the free flow of ideas, while employers who afford their employees free time to pursue pet projects, like Google, may have an easier time in brainstorming sessions. A change of environment from the typical board meeting room may be a great catalyst for a brainstorming session to let employees feel free to express their ideas. Before a brainstorming session, send out an e-mail to your employees letting them to know the problem to be addressed, and that everyone will be required to bring a unique idea to the table. This gives them time to think of not only one, but numerous ideas that will unlikely be brought by another employee.
First and foremost, make sure your brainstorming session has an effective leader, or if there are groups, several effective leaders who are capable at organizing rapid fire ideas. The group leader should write down the central idea in the middle of the paper, while coworkers begin stating related random ideas as soon as they surface. The point of this phase is to express without thinking too hard about the feasibility of the ideas - emphasizing quantity over quality. The leader should make sure all team members participate and offer their ideas. No one should sit out. After random thoughts have been exhausted, the group leader should elicit responses from his or her group with simple questions in an effort to squeeze out the last few suggestions.

After the initial phase has ended, ask team members to group these ideas into themes. If there are enough ideas, common themes will emerge. Group these into categories. Start to eliminate redundant topics and organize the thoughts into an outline format.

Now, start over with the initial problem, keeping your initial brainstorming results separate. It's time to play Taboo - the game where obvious answers are omitted in an effort to find innovative results. Take the recurring themes from the first brainstorming session and make them "taboo" for the second session. Any reference to a similar idea in the first session will not be accepted. While this process will undoubtedly be slower, it is up to the group leader to coax answers out of group members until a satisfactory amount of suggestions have been attained. Organize these answers into themes and an outline, as with the original list. This new list will be your non-conventional one.
Once the two lists have been created, converse with your group to see if any unique ideas have emerged.

For the third list, have a contest with your group members to see who can create the craziest solution, no holds barred, for the problem. Let them know that the most insane idea will be rewarded. This unrestricted contest is intended to be humorous and light-hearted, and make sure your group leader is social enough to keep up the pace.

Once all three lists have been created, have a serious discussion with your peers regarding the recurring themes and the best ideas. If you have more than one group in the brainstorming activity, compare the results. Each group can write up their best ideas and set them up around the room, and other groups can vote on their favorite ideas.