According to the IGDA, the whitepaper which provides online games market statistics, business model descriptions, and technology summaries. The whitepaper also provides online games examples and reference resources.
The intended audience of the report is "independent game developers and development studios without significant business and technology resources, which plan to create online games." The report was compiled and written by over a dozen volunteers from the professional game development community.
You must be registered with the IGDA (paid membership or free user account) to download the whitepaper. More information can be found at http://www.igda.org/Endeavors/Research/Online/online.htm.