I found a nice summary of Donella Meadow's 12 Leverage Points to Intervene in a System in wikipedia. Places where a small change can have large effects, and if you are a participant in the system, awareness and use of these means enable self-organization. Go to the page for a full description.
(in increasing order of effectiveness):
12. Constants, parameters, numbers (such as subsidies, taxes, standards)
11. The size of buffers and other stabilizing stocks, relative to their flows
10. The structure of material stocks and flows (such as transport network, population age structures)
9. The length of delays, relative to the rate of system changes
8. The strength of negative feedback loops, relative to the impact they are trying to correct against
7. The gain around driving positive feedback loops
6. The structure of information flow (who does and does not have access to what kinds of information)
5. The rules of the system (such as incentives, punishment, constraints)
4. The power to add, change, evolve, or self-organize system structure
3. The goal of the system
2. The mindset or paradigm out of which the system - its goals, structure, rules, delays, parameters - arise
1. The power to transcend paradigms