ESTA is a non-profit trade association representing the North American entertainment technology industry. Members include dealers, manufacturers, reps, service and production companies, scenic houses, designers and consultants.

The United States Institute for Theatre Technology, Inc. (USITT) is the association of design, production, and technology professionals in the performing arts and entertainment industry.

Backstage World is the website for people working in showbiz.

Theatre Communications Group.  Provides general theatre information as well as a link to ArtSearch.

Entertainment Technology Online, a great resource for technicians.

Stage Directions The Practical Magazine of Theater

TD & T is the journal for design, production and technology professionals in the performing arts and entertainment industry.

Glossary of Technical Theatre Terms
A comprehensive theatrical glossary from the UK. Some of the terms aren't applicable to the US, but a very nice resource anyway.

The Educational Theatre Association is a professional organization for teachers of theatre and theatre professionals at all levels.

High School Tech Production website is written for high school students interested in all aspects of technical theatre. A beautifully designed site with great information.

The League of Historic American Theatres is an international not-for-profit membership association for people who appreciate the cultural and architectural heritage of historic theatres and who work locally to rehabilitate and operate their theatres in communities throughout North America.

The Association of British Theatre Technicians strives to further technical standards in UK Theatre by collating, discussing and re-distributing information that relate to theatre planning, stage machinery, lighting and sound equipment, acoustic, scenery construction, stage management, education and all aspects of performance and presentation.

Foy Inventerprises Special flying effects

Opera America - the service organization for opera.

Keyword searchable MSDS database at Cornell University

OSHA Occupational Safety and Health Administration

Christie Communications Safety Related Internet Resources is an incredible list of safety-related sites.

The Great Lakes Center Health in the Arts Program has an excellent reference Library and links to safety related sites for arts workers.

Frieze Scenery Shop Safety Manual An excellent example of a safety manual for an active university scene shop written and maintained by Rich Lindsay, TD at the University of Michigan