1. A method performing a computing task comprising operations of: a coordinating computer receiving an aggregate computing task divisible into multiple independent subtasks; announcing an opportunity for other computers to participate in the aggregate computing task, and in response, one or more subscribing computers submitting requests to participate in the aggregate computing task, the subscribing computers including one or more computers having principal functions distinct from the aggregate computing task; the coordinating computer receiving the requests from subscribing computers, and in response, the coordinating computer assigning the subtasks by distributing the subtasks among the subscribing computers, and also sending an idle time activation program to each subscribing computer; each subscribing computer installing the idle time activation program, whereupon the idle time activation program causes the subscribing computer to perform operations including working toward completion of the assigned subtask when the subscribing computer is in a predefined idle state with respect to the subscribing computer's principal functions, and halting work toward completion of the assigned subtask when the subscribing computer is not in the predefined idle state; and in response to each subscribing computer's completion of its assigned subtask, transmitting results of the completed subtask to the coordinating computer.