Trade Associations:

Trade associations are generally divided into those who produce electricity and those who use electricity.

Yahoo Sites:

Electric utilities
Construction companies: power plants and transmission facilities
Electric power engineering companies

Regulation:

Wholesale trade in electricity is regulated by the Federal Energy Regulatory Commission. Most retail trade, as well as development of new facilities, is regulated by the states. Many state agencies may be involved but rates are typically governed by a state Public Utility Commission (See National Association of Regulatory Utility Commissioners for links.)

Government information:

Energy Information Administration (home page), plus:
--Electricity menu for many EIA reports and databases.
--email contacts with agency experts.

Competitive Utility -- policy analysis.
Electricity Daily -- general news. Free trial subscription.
Electricity Journal -- monthly policy analysis.
Electric Light and Power -- general news, some technical. Free to qualified readers.
Energy Insight is a daily web news and document source. Free trial subscription.

Other sources:

Infocast holds numerous seminars on current industry topics.
Electric Power Research Institute is supported by many utilities. Some of its research is public. Plus email to experts.
Pennwell has many books, directories and maps.
Resource Data International -- research reports, databases and maps.
Energy Central -- free to professionals working in the electric power industry.
Energy.com has news and other publications.
Energy Technology Data Exchange - an international consortium, owns the Energy Database, with over 3 million bibliographic citations of international energy research and development information.