I'm about to jump in my big SUV and travel 800 miles round trip. I feel a slight tinge of guilt for not doing my part to reduce my carbon emissions, so I thought I would point our readers towards offsetters.com. Offsetters will accept donations to invest in carbon neutral technologies elsewhere. If each of our readers would voluntarily donate $1 to Offsetters, I could travel guilt free.
Wait, you think I should pay for the damages from my own emissions? Obviously you haven't been paying attention. John and I provide Env-Econ for free (actually I'm free-riding off John's goodwill since he pays the TypePad bill each month). I would claim that we provide each of you with at least $1 in benefit through our entertaining and insightful posts. So instead of you paying us, I'm just asking you to pass the benefits along to others---thereby skipping the middleman and reducing transactions costs.
So now if Offsetters fails to collect enough to cover my travels, I can safely assuage my guilt by blaming our free-riding readers.