1. A method for utilizing spare resources in a cloud computing system including a plurality of computing devices, the method comprising: running a grid virtual machine instance on each of the plurality of computing devices; receiving a work request via a first application programming interface (API); determining a composite load factor on each of the plurality of computing devices, wherein the composite load factor represents the overall load on the respective computing device; examining the composite load factor on each of the plurality of computing devices to produce a first set of computing devices with composite load factors below a threshold; dividing the work request into a plurality of subtasks; and instructing, via a second API, the grid virtual machine instance running on each computing device in the first set of computing devices to process one of the plurality of subtasks.