Are there any unsolved problems for growing companies you wish someone would apply to solve?
The second-biggest problem is probably cofounder fallouts.
Internal communication and management structure are always big problems for growing companies that I wish someone would solve.
Seriously though - after attending their cofounder communication workshop, we invited them to do it for our whole team. I think Innerspace is the best tool I have seen to prevent cofounder fallouts and improve internal communication.