American Society of Professional Estimators -- Providing estimators with education, fellowship, and opportunity for professional development. Employment board, information on the organization and its chapters.
R.S. Means Company -- Construction cost software and publications, reference books, consulting services, and estimating seminars. Information on the company, on-line cost estimator, and construction dictionary.
Design Cost Data Magazine -- Publisher of estimating systems and historical construction cost data. Excerpts from the publication, and an on-line conceptual estimating system.