How to get work done?

The options for getting work done are likely greater that ever because the internet has made physical distance far less important. Options include full time employees, part time employees, subcontractor firms, and subcontractor individuals. All of these could be either local or afar. Intermediaries range from headhunting firms, to Samasource.org to Amazon's Mechanical Turk. These options are merely the most obvious. I wonder what characteristics of the work to be done determine which contractual arrangement is preferred for accomplishing tasks. For example: does the job require firm specific knowledge, are trade secrets at risk, and what is the efficient economies of scale for the tasks? My goal would be to design a short questionnaire the results of which would guide an executive toward the preferred contractual arrangement. Has this been done? Please share where. What do you think? Would it be useful?