http://www.aisc.org  -  American Institute of Steel Construction 

http://www.boltcouncil.org - Research Council on Structural Connections

http://www.astm.org - search and download ASTM specifications

http://www.nfda-fastener.org - National Fastener Distributors Association

http://www.thesefa.com - Southeastern Fastener Association

http://www.stafda.org - Specialty Tools & Fasteners Distributors Association