11. A computing system configured to act as an intermediary to facilitate performance by task performers of tasks submitted by task requesters, comprising: one or more processors; and a task fulfillment facilitator system configured to, when executed by at least one of the one or more processors, facilitate performance of multiple tasks by, for each of the tasks: receiving information from an executing program of a task requester about the task available to be performed, the information received via a defined programmatic application program interface and indicating one or more criteria for satisfactory performance of the task; providing information about the task to one or more human task performers who are qualified to satisfactorily perform the task based on the indicated criteria; and after receiving results based on performance of the available task by one or more of the human task performers to whom the information about the task was provided, supplying the received results via the defined programmatic interface to a program of the task requester.
14. The computing system of claim 11 wherein the task fulfillment facilitator system provides an electronic marketplace to which multiple task requesters submit available tasks to be performed and to which multiple human task performers unrelated to task requesters provide results from performance of tasks submitted by those task requesters.