Asianart.com (many useful resources, including a list of associations, exhibitions [with links to online websites], articles, and galleries; "on-line journal for the study and exhibition of the arts of Asia")
DIDO: Digital Images Delivered Online (75,000 images encompassing the full breadth of art historical periods and media; from IU's School of Fine Arts)
Online Museum Resources on Asian Art (OMuRAA) (index to online Asian art collections, digital image libraries, special exhibitions, and related information; initiative of the Asia for Educators Program at Columbia University)
Visual Information Access (VIA), Harvard University Library (electronic database of visual resources, including historic photographs and other images; search by keyword; full-sized images are restricted to Harvard users, but thumbnail images and other information are visible to all)
CENTRAL EURASIA & CAUCASUS:
Abdul Hamid II Collection (1,819 photographs, dating ca. 1880 to 1893, during the reign of the Ottoman Sultan Abdul Hamid, r. 1876-1909; collection held by US Library of Congress)
Ernst Cohn-Wiener Collection (ArchNet) (a digital collection of hundreds of photographs taken 1924-1925 of architectural monuments in West Turkestan and supplemented by more recent photographs)
Images of Russia and the Caucasus Region 1929-1933 (over 700 images of Russia and the Caucasus region, particularly of rural areas in Georgia and Dagestan, taken by William O. Field; William O. Field Collection, American Geographical Society Library of the University of Wisconsin-Milwaukee Libraries)
Prokudrin-Gorskii Collection (2,607 photographic images of the vast Russian Empire--including Central Asia and the Caucasus--made between ca. 1905 and 1915; keyword search; collection held by US Library of Congress)
Turkestan Album (Turkestanskii Al’bom) (online copy of this famous work produced under Russian colonial rule, digitized from a copy held by the US Library of Congress; contains approximately 1,200 photographs, architectural plans, drawings, and maps)
SILK ROAD:
Digital Silk Road (content in Japanese and English, depending on the project; from the National Institute of Informatics, Japan)
Yale Silk Road Database (over 11,000 digitized photographs taken during summers 2006-2010; poorly constructed interface--"browse" collection by using the Search box in upper right)
Tibet from the collections of the American Geographical Society Library (includes early photographs of central Tibet and Lhasa taken by G. TS. Tsybikov and Ovshe Norzunov, Russian-Mongolian visitors to central Tibet in 1898-1901, as well as images from Harrison Forman's expeditions to northern Tibet in 1932-1937)