Online Museum Collections and Libraries:
The Metropolitan Museum of Art – Link to the searchable collection at the Met, lots of high resolution detailed photos of their arms and armor collection.
The Wallace Collection – Link to the searchable arms and armor collection at the Wallace in London.
The Royal Armouries – Link to the searchable collection at the Royal Armouries in Leeds, UK.
Philadelphia Museum of Art – Link to the searchable collection at the Philadelphia Museum of Art.
Detroit Institute of Arts – Link to the searchable collection at the Detroit Institute of Arts.
Art Institute of Chicago – Link to the searchable collection at the Art Institute of Chicago.
Worcester Art Museum, Higgins Armory Collection – Link to the searchable collection of the Higgins Armory Collection at the Worcester Art Museum.
Kunsthistorisches Museum, Vienna – Link to the searchable collection at the KHM, Vienna, Austria.
Musée de l’Armée – Link to the searchable collection at the Musée de l’Armée, Paris, France.
Bibliotheque Nationale de France – Online high resolution scans of the collection from BNF including lots of medieval manuscripts.
The Morgan Library – Medieval manuscripts housed at the Morgan, including the famous MS M. 638, the Maciejowski Bible.
Bodleian Library – More high quality digital images of manuscripts from the Bodleian Library at Oxford.
The Getty – Link to the collection of the JP Getty Museum.
The British Library – Link to the British Library’s collection of online images.
Powerful internet-based resources for researching the Middle Ages:
Manuscript Miniatures – An incredibly robust search engine and database of the miniatures from over 1,500 medieval manuscripts. This database grows constantly. Here you can search by year, location, use different tags etc. to narrow your focus and get a good artistic survey of the objects or time periods you’re after. Click through the images to be taken to their sources.
Effigies and Brasses – Sister site to Manuscript Miniatures, this site boasts the same breadth, depth and searchability, only this time we’re dealing with Medieval funeral effigies and brasses. A word of caution, many of the images to be found are line-drawings of the original sculptures or brasses so some detail is inevitably lost, but there are still many photographs of the actual objects themselves.
Armour in Art – Another companion to the two previous listings. Armour in Art covers artistic depictions in art from media other than manuscript illuminations. This database is smaller and newer than its bigger brothers but still contains a wealth of knowledge and information.
Larsdatter – Very thorough set of searchable links to all kinds of categorized objects within the realm of Medieval material culture thanks to Karen Larsdatter. Looking for hoods? Search hoods and be brought to a several links, listed by chronological order of their depictions. More interested in spoons? Lanterns? You name it, it’s probably got a good starting point for you to open up your research.
Portable Antiquities Scheme – Very large searchable database of archaeological finds from England and Wales. The search function sometimes returns strange results, but if you’re persistent or clever with search criteria you can find a lot of very interesting objects.
An Analysis of 1300 Effigies Dated Between 1300 and 1450 – Doug Strong’s analysis of over 1,300 funeral effigies and brasses of the 14th and early 15th century. This is a great place to see summarized, the trends in the types of armors appearing on effigies in a given region or decade.
Internet Forums that include good Medieval discussion:
MyArmoury – Very valuable discussion forum. High-level discussion is present here on all sorts of topics related to historical arms and armor, ancient, medieval, renaissance, early modern etc.
Armour Archive – Another fantastic discussion form for arms and armour. The Armour Archive has lots of knowledgeable and renowned posters in the armoring world. The Armour Archive is very SCA-centric at times, so just make sure you’re clear about what you intend to use armor for if your questions involve that.