1. A method in a computing system for providing an electronic marketplace that acts as an intermediary to facilitate purchasing and selling human-generated answers to questions, the method comprising: for each of multiple users unaffiliated with the electronic marketplace, receiving information from the user regarding availability of the user to act as a human task performer, the received information including current qualifications of the user related to performing tasks, and registering the user at the electronic marketplace as an available human task performer; in response to each of multiple tasks submissions that are each received from an application program of a task requester via a programmatic interface of the electronic marketplace to make a submitted task available for performance by human task performers unrelated to the task requester, registering the submitted task at the electronic marketplace as being available, each task submission specifying an associated fee and associated qualifications and associated task performance criteria for the task such that the fee is to be paid to a human task performer who has the qualifications and who satisfactorily performs the task by answering a specified question for the task in such a manner as to satisfy the criteria; and for each of at least some of the registered tasks, providing information about the task to one or more human task performers, the provided information including the specified question for the task; receiving an answer generated by a human task performer for the specified question of the task; and when the human task performer who generated the answer has current qualifications matching the associated qualifications for the task and when the associated criteria for the task are satisfied, providing the received answer via the programmatic interface to the application program that submitted the task and providing the associated fee for the task to the task performer, so that application programs can programmatically purchase answers to questions that are provided by human task performers.