IAAO
International Association of Assessing Officers - an educational and research body for people with an interest in property taxation. http://www.iaao.org/
Appraisal Institute
Find a qualified appraiser or read about what they do, when and why you need an appraisal, and how to get a copy of your appraisal report.
NCREIF
Nat'l Council of Real Estate Investment Fiduciaries represents investment managers, accountants, appraisers and other real estate professionals.
Appraisal Institute of Canada
National society of professional real estate appraisers promotes standards for members by granting CRA and AACI designations.