Broadway classic musicals from 1927-1969. It is much more than a "fake book," with plenty of illustrations and revealing insights into the long running musicals, but I think you have to be a serious fan to shell out 60 bucks for this two-volume set.
It is one of many interesting titles due out in the coming months. A collection of Ring Lardner came out in August, which tempts me a great deal. A set of early Elmore Leonard novels also caught my eye. There's also a new collection of Louisa May Alcott, keeping in their classical vein.
Library of America has grown to over 200 volumes since it was established in 1979, and is making a concerted effort to keep up with the times. It has covered an impressive range of topics over the past 35 years, from the colonial years of America to contemporary journalism, with just about every piece of Americana in between. LOA still provides subscriptions, but you can find their volumes through most book suppliers, although you might not necessarily get the slip case that comes with direct purchases.
Among my personal favorites are the Writings and Drawings of James Thurber and The Oregon Trail, The Conspiracy of Pontiac by Francis Parkman. What are your favorite titles?