Abiti Antichi — In Italian. Lots of beautiful pictures of someone’s collection of extant clothing from the 18th century through the 1930s. Easy to navigate, even if you can’t read Italian. There is one page in English that explains the site.
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.”
Bay Area English Regency Society — San Francisco bay area group that “celebrates the spirit of the early 19th century.” Hosts balls throughout the year. Site has links to other Regency sites.
Before the AutomobileNew! — Blog by Finnish woman about 18th & 19th century clothing. Includes lots of photos of her beautiful creations.
Candice’s Collection — Candice Hern’s collection of regency items, including fashion plates, prints, silhouettes, quizzing glasses, reticules, buckles, etc.
Regency Colors — A page with examples of colors, like Coquelicot and Jonquil.
Regency England — Articles on regency clothing, popular colors of the time, cosmetics and more
Regency Fashion Page, The — Great site!! Covers most aspects of fashions of the era. Sections on extant clothing, fashion plates, portraits and styles by year. (Site seems to be partially at "http://locutus.ucr.edu/~cathy/reg3.html" and partially at "http://regencyfashion.org/")