The Walters Art Museum of Baltimore, Maryland, has been digitizing some of its holdings and making them available on-line. And, perhaps unsurprisingly, some of these holdings are heraldic. The books below, and all of their other books, can be found in a listing on their website at http://www.thedigitalwalters.org/01_ACCESS_WALTERS_MANUSCRIPTS.html All of these books can be read on-line, or you can download and save some or all of their pages in varying resolutions and in two different formats, .tif and .jpg.
The first book I want to bring to your attention is one of English heraldry, dated 1589, with arms dating from before the Conquest in 1066 (and since heraldry as we define it did not exist then, these are, of course, coats of arms attributed to the bearers, e.g., the Saxons) into the reign of Elizabeth I. This book can be found at: http://www.thedigitalwalters.org/Data/WaltersManuscripts/html/W847/
The second book is entitled English Brasses, “written & illuminated & bound by John Woodcock 1949." It is a very brief history of English brasses from before 1350 through the 18th Century, with drawings of brasses to illustrate each period discussed. It can be found at: http://www.thedigitalwalters.org/Data/WaltersManuscripts/html/W769/
And finally, there is an Album of the House of Savoy, in Latin and dated to the 16th Century. It is mostly illuminations, and the paintings - as you can see from the example above - often have heraldry in them. This album can be found at: http://www.thedigitalwalters.org/Data/WaltersManuscripts/html/W464/
There are, of course, a lot of other manuscripts and books there, ranging from single leaves to entire books, but these are the heraldic ones that jumped out at me, and I just had to share them with you.