Perhaps Santa's bag wasn't quite as heavy this year. Barnes & Noble booksellers reported Thursday that digital books are now selling better than physical ones on the company’s website—and that it sold nearly 1 million e-books on Christmas Day alone. Meanwhile, the company's e-reader, the Nook, has become its biggest-selling item in history. Rounding out a good season for e-readers, Amazon.com announced Monday that its e-reader, the Kindle, has become its bestselling item ever, outselling Harry Potter and the Deathly Hallows. Forrester Researcher expects e-book sales to total $2.8 billion in 2015, up from $1 billion in 2010.