Here are some links that you absolutely MUST see if you make armour, or are interested in armour at all. Some of them are valuable resources, some of them have excellent picture archives, and only a few of them will be arbitrary links that I put there.
Armour Construction and Resources Links
An excellent site featuring forum discussion about armour construction, pattern library, classifieds, and various pictures archives and links. A must see!
Another excellent site featuring many different discussion forums, a large pattern archive, and an auction/classifieds section. Another must see!
This is a great page for both maille and plate. Matt is a great guy in Ontario who is "The budding mid 14th century German Transitional guy." He's making some great sabatons and splinted pieces. Check him out! He even likes helping people (advice only if you're too far away =P) make armour of their own!
A great resource for both post rivets and roofing nails (arming nayles). Great prices and customer service!
Another great resource. They carry just about everything. Rivets, wire, tools, etc. Take a look at their extensive catalog!
Blacksmithing supplies. Swage blocks, hammers, forges, and much more. Great products and customer service!
Autobody supplier that carries many finishing products, power tools, and of course the renowned Beverly Shear!
Chivalry Links
A Mystic Order of Chivalry (the one that I belong to). Check it out.
The Knighthood, Chivalry, and Tournament Resource Library. Great site.