So let's say a certified investing company emerges that will take the small investments of people like us and combine them into large rounds of investments. They do this in rounds saying that after 6 months or so, they'll sit down with a company that has had interest shown and work out deals that can be voted on by the people interested in investing.

How would this be fundamentally different from a public stock exchange, except that investments would be much slower than the instantaneous trading we can do now?