I am not convinced that the bigger problems to the world have answers which can be provided by a 'start up', and feel that the tendency toward "X-is-broken" type start up pitches tend to suggest techno-fixes to problems of social structure.
only the organised struggle of the disenfranchised of the world can end class society, eliminating both the bourgeoisie and the proletariat, providing a ground on which these problems can be usefully approached. No venture capitalist is likely to invest in this, unfortunately.
In direct answer to your question: voluntary associations of the toiling masses
> voluntary associations of the toiling masses
With the mighty overhead of just-plain-survival (the main reason that the poor tend to stay poor), I'm sad to say that's never going to happen.
I think what humans as a species really needs is a planet wide support system that takes care of the food/shelter/clothing/sewage problem. But we're so deeply wired for paranoia, group think, and solipsism that that's impossible too.