Editor's Note: The following post comes to us from contributing expert Panos Ipeirotis. It was originally posted on his blog.

Last September, I was visiting CMU and a student asked me a question: "Do you know any crowdsourcing market where we can assign tasks to people, as opposed to waiting for the workers to pick the tasks they want to work on?"

Most crowdsourcing services do not satisfy this requirement. Mechanical Turk, oDesk, eLance, and all others typically expect the workers to express interest in a task. At most, you may be able to invite workers to participate in a task, but you cannot really assign a task to a worker.

A notable exception is Fiverr, which plays the supply side of the market; however, Fiverr has a different limitation: The tasks that can be performed are posted by the workers, and the employers pick from a set of existing tasks.

After thinking for a while, I realized that there are more such markets in which you can assign tasks to "workers." The main difference is that the "workers" are not necessarily humans, but APIs. Enter the world of Mashape, an API marketplace. Are you looking for someone to classify tweets according to their sentiment? Query the Mashape marketplace for sentiment analysis APIs and then assign the task to the intelligence units of your choice.

With the advent of the API marketplaces, we see the emergence of marketplaces for "intelligence units." All these intelligence units (APIs, or human workers) have different levels of quality, various levels of pricing, and even various levels of capacity and responsiveness.

With the proper abstraction, a task management platform can use and optimize these distributed intelligence units without having to worry about the "implementation details" of this intelligence.

- Panos Ipeirotis is an Associate Professor and George A. Kellner Faculty Fellow at the Department of Information, Operations, and Management Sciences at Leonard N. Stern School of Business of New York University.