Society for Creative Anachronism (SCA)- Selectively reenacting the middle ages.
Encyclopedia.com- good general reference site.
Bravenet Web Services- great free tools for webmasters!
Add Me!- add your site to 30 search engines.

• Drafting Patterns for Medieval Garb
  Some excellent, simple patterns here, mainly for early medieval english clothing.
• Medieval Clothing Pages: Articles by Cynthia Virtue
  Great information here! Mainly to do with hats and headwear. I especially like the article on how a veil should be worn. If done right it can be very gracefull.
• Elizebethan Costuming Page
  An excellent page for later period costume. Great corset patterns! I recommend the tabbed corset though... your hips will thank you if you have to wear it for any length of time.

• GodeCookery.com
  The best page I have ever found about medieval food and cookery, and it looks as though it's still being built! If you want to know what people ate and how they made it, this is definetly a good place to start.

• Fransesco Sirene, Spicer
  If you need hard to find spices for a medieval recipie, this is the place to look!
• Historic Enterprises
  Sell medieval and renaissance clothing and accessories.
• Jas. Townsend & Son Inc.
  These guys sell reenactment goods, mainly from the 18th century, but some of the things they sell can be very useful within the timeframe of the SCA (medieval age), pre-cut quills are just one example.
• By The Sword
  Affordable accessories for the medievalist, although some of the items are of dubious historical accuracy.
• Museum Replicas Limited
  A lot of interesting things here, and the prices are pretty good.
• Renstore.com
  Medieval and Renaissance clothing and accessories.
• The Pillaged Village
  Highly recommended! Mainly accessories to be found here. Great prices, a great resource for trims, clasps and buttons too.