On August 29, 2016 the FAA opened the door to proper authorization for flying small unmanned aircraft ("drones") for commercial purposes. Prior to that date, the regulations weren't very clear about non-recreational operations but now there is little left to that former grey area. Skygear Solutions created and actively administers a large forum on Facebook called, "Commercial sUAS Remote Pilots." Feel free to join this group for further discussion and posting questions about your interests in flying drones commercially.
If you are planning to operate your drone(s) for commercial purposes, you will need to be in compliance with the Federal Aviation Regulation, 14 CFR Part 107. This is the new set of rules specifically for flying unmanned aircraft in the U.S. which don't fall into the category of Model Aircraft (See 14 CFR Part 101.41, Special Rule for Model Aircraft / Section 336 of the FMRA, and AC97-51A).
Anyone who wishes to fly drones commercially will either need to update their manned aircraft pilot license or take a separate exam developed by the FAA. The Unamnned Aircraft General (UAG) Exam consists of 60 questions and costs $150 to take. Below, you will find a list of documents and a selection of videos which will help guide the test taker through the information contained within the exam.
Part 107 Summary
This is an outline of the new commercial drone rules released by the FAA
Part 107 Advisory Circular
Guidance for flying commercially under Part 107
Remote Pilot Study Guide
Comprehensive study guide from the FAA for the UAG Exam
RP Knowledge Test Guide
Information for preparing to take the UAG Exam
A complete listing of knowledge areas covered by the UAG Exam