Christmas Day is the heaviest day of the year for digital content sales and downloads, and this year’s could be even bigger, Reuters reports.

About $10 million was spent on this category on Christmas Day last year, Reuters said, based on information from comScore. The second busiest days were Dec 26 and Dec 27, it added.

This year may well be no different: digital goods are already the fastest-growing category online this holiday, up 30% compared to the same period last year, compared to the 15% e-commerce sector’s average increase.

As you can imagine, this growth has been fueled by record sales of e-readers and tablets. This trend is also likely to remain solid after Christmas, as many iPad 2s, Nook Tablets and oKindle Fires were bought as gifts and haven’t even been unboxed yet.

As we reported, Amazon recently announced that it has been selling over one million Kindles a week for the last three weeks. The company also seems prepared to do what it takes to boost the digital sales it will result in, and will run discounts on digital goods on Christmas Day and the days that follow, Reuters reports.

According to Andrew Lipsman of comScore, quoted by Reuters, “the real new growth is coming from e-books. People are downloading e-books in a way they had not previously.”

Besides e-books, digital goods also include music and videos, a category that companies other than Amazon will also promote heavily next week. Apple, for instance, will be running a Boxing Week music promotion on iTunes in the Americas and Europe.

Who said no one would pay for digital content?