I often find that an author's lesser-known works are among my favorites; some examples are Steinbeck's "Tortilla Flat" and "The Wayward Bus", Jack London's "The Road," and Twain's "The American Claimant" (not to mention Grisham's "A Painted House").
I know that "The Innocents Abroad" was Twain's most popular book (in terms of number of sales) during his lifetime, but since then, I would imagine it has been overtaken by "Tom Sawyer" and "Huck Finn" and possibly others.
I would like to know, particularly, where "The American Claimant" fits in among Twain's other works. Mulberry Sellers is, IMO, one of Twain's most entertaining and fascinating characters - perhaps without peer among his protagonists - after Huck Finn and Tom Sawyer, that is.
Is there an online site that would show, filtered by author, how many copies of each of an author's works have sold? Even if it was just ordered by rank (1..N), rather than numbers of sales or copies printed, I would find it very interesting.