Here are a few resources you may find useful.

Standards
ISO http://www.iso.org
SAE http://www.sae.org
DIN www.normas.com/DIN/indexes/index.html
ASTM http://www.astm.org

 

Government Resources
Defense Logistics Information Service http://www.dscp.dla.mil
FAR Federal Acquisition Regulation http://www.arnet.gov/far
Search Government Specifications for Military parts http://assist.daps.dla.mil/quicksearch/
Fastener Quality Act http://www.uspto.gov/web/offices/tac/fqa/t15p280.htm 
Fastener Insignia Register http://www.uspto.gov/web/offices/tac/fqa/active.pdf

 

Fastener Links
NFDA http://www.nfda-fastener.org/
Fastener Company Search http://www.e-fastener.com/html/companydirectory.cfm
Surplus Fasteners https://www.fastenersclearinghouse.com/fch/main.nsf/fSearch
Maximum Torque Values for Screws and Bolts http://www.thelenchannel.com/1torque.html
Thread & Head Specs http://www.americanfastener.com/techref/machine.htm
Hole Size & Torque http://www.engcomponents.com/techinfo.htm
Global Engineering Documents http://global.ihs.com/
Conversions http://www.convert-me.com/en/

 

Fastener Associations MAFDA MANA MFDA