LibraryThing, the social book cataloguing site, hosts a number of "legacy libraries" which recreate the book collections of historical figures. The initial project, launched in 2008, focused on Early American private libraries, but the scope has since been widened to include libraries from other countries. Over 150 libraries have now been completed, with 50 in progress and many more proposed. Among 18th-century libraries are those of Jefferson, John Adams, John Hancock, and of course Washington, as well as both Johnson and Boswell. There is also a partly completed Voltaire library which contains 3,746 books. Enthusiasm for the Voltaire project seems to have fizzled in 2013 - understandably, given both the size of Voltaire's collection and the fact that a definitive print catalogue, published in the Soviet Union in 1961, already exists.
The only 18th-century French library to be fully entered to date is a slightly unexpected choice. It is Marie-Antoinette's personal library from the Petit-Trianon, which was originally catalogued by Paul Lacroix in 1863. The collection contains 736 books, mostly novels and plays [tagged Belles-lettres (475), Romans (179), Théatre (177)]. Unfortunately there are no pretty cover pictures which is one of the best features of LibraryThing accounts. I was also a bit disappointed to learn that I share no books with M.-A. and that we have no titles that can be recommended to one another....
LibraryThing "legacy libraries":
Marie Antoinette's library: