Milieux - The Costume Site 
A web index for costumers and those interested in costume. History, images, research, museums, instruction, organizations, events, and large source/suppliers listings.
http://www.milieux.com/costume/The Costumer's Manifesto 
Includes photographs, renderings, history and information on costuming. Extensive links collection.
http://www.costumes.org
Cyndi's List - Clothing & Costumes 
General resource sites, accessories, regional, preservation, and vendors.
http://www.cyndislist.com/clothing.htm
The Costume Gallery 
Directory of costume resources. Period clothing and hair styles, courses on period clothing and its construction, research library, and consultations.
http://www.costumegallery.com/
The Costume Page 
A comprehensive index of costume links for those who study and/or make costumes.
http://www.costumepage.org/