In order for that to be of real use, you would need to develop the architecture of ideas better. I have a little sandbox blog for doing that, but, like so many things I do, it is kind of on the back burner.
By architecture of ideas, I mean that there is a big difference between, say, some off the cuff random idea written out in a paragraph and the same idea backed by the same number of words but filled with years of experience, research, and refining the idea. So there is a big difference between a glib one-liner thrown out by an "armchair politician" and a succinct one line mission statement that has a density of information and ideas in it.
If you want this to be more than just shooting the shit -- if you want it to be meaty feedback on which ideas might actually fly as businesses -- you will need to put in place that architecture, as well as a development process. At that point, it is more than just a forum. It is a vehicle for development.