Vincent Van Gogh's 902 letters from and to him, now available online freely. The letters are translated into English and richly annotated and illustrated with new transcriptions and translations edited by Leo Jansen, Hans Luijten and Nienke Bakker for the Vincent Van Gogh Museum in Amsterdam and the Huyghens Institute - KNAW.
The datasets that are offered cover a range of topics relating to Dutch history and are particularly strong in aspects of socio-economic and colonial history. The datasets can be browsed or searched by keyword. Users need to register in order to be able to download datasets.
A large collection of images of medieval manuscripts however you can't zoom to a close focus and there aren't translations, except for a brief description of what each page on the manuscript contains.
Excellent images of the manuscripts to a high level of detail, however no translations available. When will these people realise that everyone's Medieval Latin is a little rusty these days?
This site is briliant! A bunch of exemplary librarians maintain a list of high-quality sites which can be used for historical research on Europe. It's especially good for World War One but also some of the smaller European countries which are often hard to find information on.