Doubleday reported more than 500,000 readers took advantage of the free e-book download of The Da Vinci Code which included an excerpt from Dan Brown’s forthcoming thriller Inferno (on sale May 14th). The e-book offering, in celebration of the book’s 10th anniversary, was available to readers through all digital retailers for seven days. Coincidental with the e-book promotion, booksellers received a special slip-cased hardcover anniversary edition of the book with a thank you note from Dan Brown.