An absolutely fantastic new digital offering from the New York Society Library: their earliest surviving charging ledger, covering the period July 1789 and April 1792. This is a true delight, since you can not only browse or search by borrower (and they've got some good ones, like George Washington, John Jay, Rufus King and Alexander Hamilton), but also find short sketches of each borrower, see who else borrowed each book (here's Jefferson's Notes on the State of Virginia, for example), and see the listing for each book in the library's early catalog (or in the OPAC if it's still in the collections).
Truly delightful!