American Iron and Steel Institute
www.steel.org 

The American Society for Testing and Materials
http://www.astm.com

DeKalb Forge Group (Aluminum, Brass, other forging in mid to low volume)

http://www.dekalbforge.com

The Forging Industry Association
http://www.forging.org

General
http://www.forgings.bz
http://www.industrialquicksearch.com
http://www.thomasnet.com

Lefere Forge (Symmetrical - hot forgings 5 to 160 pounds)
http://www.lefereforge.com

Modern Forge Group (Non-symmetrical - hot forgings ounces to 70 pounds)

http://www.modernforge.com

Quality steeel Forgings (Small press forgings)

http://www.qualitysteelforgings.com

Sharp Edge Tool

http://sharpedgetool.com

Southwest Metal Products Ltd. (Net / Near Net Cold Forgings)
www.southwestmetal.com