Australian Dress Register — “The Australian Dress Register is a collaborative, online project about dress with Australian provenance pre-1975. This includes men’s, women’s and children’s clothing ranging from the special occasion to the everyday.”
Berger Foundation — Images collected by Jacques-Edouard Berger of ancient artifacts from China, Egypt, India and Southeast Asia.
Canadian Historical Portraits — Collection of portraits from Canadian history, from the 16th-20th centuries. The collection was created by Aegidius Fauteux, which was acquired by the Bibliothèque du Montréal.
Centre Nationale du CostumeUpdated! — In French, images of theater costumes, listed by time period. Includes bios of the costumers. Tres cool!
Dreamstress, TheNew! — (NZ) Blog about historical fashion of the 18th-20th centuries. Lots of tutorials on sewing techniques, how-tos, etc. She also blogs about every day clothing and has a small line of modern fashion patterns.
Early Period — From the website: “Early Period is published quarterly...for the advancement of early period arts, crafts, sciences and research. Early Period deals in the pre-1066 A.D. topics of interest to persons with early period personae in the SCA or similar organizations.”
Life Magazine Photo Archive — Hosted by Google, an archive of images from Life magazine. “...stretching from the 1750s to today. Most were never published and are now available for the first time through the joint work of LIFE and Google.”
Lileks.com — This site has lots of fun & interesting stuff from the 20th century, like images from old Sears catalogs, advertising, postcards and more.
Old & Interesting — The history of housekeeping, household antiques, domestic objects. Costume related info includes irons for frills & ruffles, laundering equipment, etc.
Online Etymology Dictionary — Database of the etymology of words in the English language. Includes pronunciation, history & origins of words. Includes slang terms. Useful if you want to know if a word was used “in period.”