We're constantly digitizing new material at my library, which is Harvard's largest for rare books and manuscripts. I post about larger collections on our blog, but I wanted to have a place to put interesting single images as well. Right now, I plan on posting one new item per day. Each image links to the record in our online catalog, for anyone who wants to know more about the source or come in to see it in person.
I'm one of the contributors to the blog of Houghton Library, Harvard's primary repository for rare books and manuscripts. This year we've inaugurated a new feature called You've Got Mail, which highlights a letter from Houghton's collections every Friday. Posts so far have included letters from Ben Franklin, Herman Melville, Rene Descartes, and the conjoined twins Chang and Eng.