I agree with Rick. The best way is to form a core group or "committee" that can get things organized first. The committee members could even setup a charter so that the group can remain focused on goals rather than run ad hoc, which happens many times a group has been created. This not to say that a brain-storming session isn't out of the scene, nor are future changes not allowed once the charter is setup.

This is something I learned when working with my online classes. I had to participate with teams during each class. We were given projects that we had to complete as a group. Some members participated more than others, and some seemed to take over the group to run it themselves.

With members spread worldwide, this can become a hassle for communication. One of the things I did learn from the online experience is that having a single meeting place, in my classroom it was the online team folder, to hold virtual meetings, and exchange ideas.
The reason for the online meeting place was so no one was left out of the idea process.

Once the intial group is setup, then you can present it to the public. With your framework in place, you'll have something to hold on to and build on frome the base.

I hope this helps.

John