Superman The Golden Age Omnibus. It'll be 784 pages of Golden Age goodness, reprinting the very first adventures of the Man Of Steel from Action Comics #'s 1-31, New York World's Fair Comics #1, New York World's Fair Comics 1940, and Superman #'s 1-7. I have all of these stories reprinted in the various Superman and Action Comics Archives but it'll be neat to see them reprinted in a bigger size and hopefully in good quality. These various covers from this period should whet your appetite for this book.
Grand Comics Database for the cover scans. I think this book will definitely be money well spent.