NERO:
NERO VALOR - VALOR forums
NERO VORPL Site currently down. - VORPL forums
NERO METRO - METRO forums
NERO WAR
NERO PRO - PRO forums
NERO ARGO - ARGO forums
NERO POLAR - POLAR forums
NERO East Tenessee
NERO International
Nerotics E-zine

Costuming:
NERO Massachusetts Costuming Links
Ye Olde Armour Shoppe Various armor products.
Medieval Menangerie
Larpware - Various armor, premade boffer weapons, boffer weapon supplies (foam, ultra-light cores), and some costuming supplies. Occassionally down.
RenStore
Silk Roads Armor
Ogworks Armor

Leather Worknig Supplies:
Brettunsville - Leather supplies if you want to make your own leather armor, belts, etc. Uses paypal for transactions.
Bythesword.com - Leather supplies if you want to make your own leather armor, belts, etc. Uses paypal for transactions.
Hide and Fur

From old VORPL board post, forgot the author:
Inexpensive Hide
Studs & etc.
Tools
Everything, but occasionally expensive

Prosthetics:
Lyonshell Masks
Tower of Ein - Connected to the Lyonshell Mask company.

Various sites and subpages for fangs (from Kel's post on Ezboard):
Easley's Fangs
Funfolly
Fangs.com
Cinema Secrets -also has general prosthetic pieces

Other Resources (non-larp):
Assoc. for Renaissance Martial Arts
Academy for Medieval Martial Arts
Sword Forum International
Dylan's page on Fencing (Semi-SCA)
Grey Company Trebuchet Page - Grey Co. Home
Total Warrior Magazine