Project Gutenberg - The first and largest single collection of free electronic books, or eBooks. Currently has over 25,000 books.
The Internet Archive - This non-profit organization was founded to build an Internet library, with the purpose of offering permanent access for researchers, historians, and scholars to historical collections that exist in digital format. Founded in 1996 and located in the Presidio of San Francisco, the Archive has been receiving data donations from Alexa Internet and others. In late 1999, the organization started to grow to include more well-rounded collections. Now the Internet Archive includes texts, audio, moving images, and software as well as archived web pages in our collections. At the moment, it has 138,364 movies, 60,063 concerts, 304,807 audio recordings, and 547,917 texts. Big collection of links as well.
Internet Medieval Sourcebook - Pretty extensive collection of medieval documents translated into Modern English. Most are free of charge.
Medieval History Texts in Translation - A few more translated texts, dealing with the Crusades and Norman Italy.
The Novgorod Chronicle - Translated into English.
BibliOdyssey - A large collection of scanned illustrated books of all kinds.
MagazineArt.org - Vintage magazine cover and advertising art from the Golden Age of American Illustration.
Historic Photo Archive - Small but growing collection of old photos. You can even order prints from the photographer.
Silk Road Seattle - Maps, photos, historical texts, and other resources on the cultures of the Silk Road across Eurasia, from the beginning of the Common Era (A.D.) to the 17th century.
Southeast Asian History - Links to the history and cultures of Asia from ancient to modern times. Articles, discussions, maps, and other resources.
Emperors of the Sangoku - Rulers of the “Three Kingdoms,” of India, China, and Japan. Includes tables, maps, and chronologies.
The Spice Routes - Details on the ancient spice routes between Southeast Asia and Africa.
Southeast Asian Monuments - Shows 100 slides of monuments in Burma, Thailand, Cambodia and Vietnam documenting Hindu and Buddhist structures, dating roughly from the 9th to 15th centuries. With overview, sculptures, and ornamental details.
The Red Kaganate - Focus is on Eastern Europe, Western Asia, and Central Asia, including Arabs and Jews. Events calendar, clothing and weaponry, heraldry, food, public forum, newsgroup, and resource links.
Steve Bartrick Antique Prints and Maps - Features maps and prints. Located in the UK.
Parallel History Project on Cooperative Security - The Parallel History Project on Cooperative Security (PHP, the former Parallel History Project on NATO and the Warsaw Pact), provides new scholarly perspectives on contemporary international history by collecting, publishing, and interpreting formerly secret governmental documents.
Internet History Sourcebooks Project - Fairly large and comprehensive site. Has links not only to Modern, Medieval and Ancient History but also breaks it down further into African, Jewish, Indian, Islamic, etc. There's even a section of how the various time periods have been depicted in films as well as Traveler's accounts.
German medieval songs - Period songs for different occassions. Includes complete lyrics.