First of all, everybody on this list is perturbed about capitalist exploitation, so there's no need for the cheap shot in your last sentence. Second, "how do we solve the free rider problem?" is the wrong question to ask, much less answer. The crucial question here is "In a socialist society, how do we ensure that we accomplish all of the important work?" Saying "some people will see the benefits and take care of it" seems like a pretty weak argument to me.
As much as I detest parecon, there is a need for some systematic planning in industrial societies. Now, we can do that planning in a democratic way, and as colleagues we can hold each other accountable for getting the important work done without a police state. I just don't see how this can be left to individual perogative. (Granted, that may reflect my lack of imagination about possible future societies, but that's how I see it right now.)
It just occurred to me that this "no coercion" position is an ideological precipitate of capitalist social relations. Under capitalism, the individual is supreme; personal choices supposedly lead to optimal allocation of resources; government screws up the optimal allocation. In the same way, the "no coercion" position assumes that we can just trust individuals to make the right personal choices, and all the work will get done. At the ideological level, both the capitalist and the no coercion perspectives are glorifications of the individual and the sanctity of individual preferences.
Perhaps this is why we shouldn't spend much time drawing blueprints for our glorious socialist future: much of what we imagine is conditioned by the capitalist social relations in which we are enmeshed. In a real sense, how to allocate work in a socialist society isn't our project. We need to do political work now to make it possible for people at some point in the future to grapple with that project.
Miles