ASTM International - Standards Worldwide
http://www.astm.org/

Society for Maintenance & Reliability Professionals
http://www.smrp.org/

Nondestructive Testing Information Analysis Center
http://www.ntiac.com/

Vibration Institute
http://www.vibinst.org/

SPIE - The International Society for Optical Engineering
http://spie.org

eFunda - Fundamentals of Engineering Online
http://www.efunda.com/

Engineering.com
http://www.engineering.com/content/index.jsp