With holiday packing comes fraught decisions. The weighty new Philip Hensher, which you rushed to buy in hardback, takes up 20% of your cabin baggage allowance. Do you a) save The Emperor Waltz for your return, when you won't read it because it's too bulky for your commute, or b) fork out another tenner for the Kindle edition?

Soon there might be a third option: open the BitLit app on your smartphone, photograph the dustjacket, write your name on the copyright page, snap that, then – magic! – a free or discounted ebook version lands in your inbox.

BitLit is a Canadian startup that answers the question many e-reader users have pondered at some point: why can't I download a free or cheap ebook version of a print book I already own? Especially now it's legal to rip your CDs on to iTunes.

Modern readers like to mix it up: we still love print, but also enjoy the portability (and search function) of an e-reader. However, the practice of "bundling" ebooks with p-books has been slow to take off; partly for technical reasons, but also because of fears about devaluing ebooks.

BitLit, which offers 20,000 titles through its website, has just teamed up with HarperCollins US for a pilot. Owners of selected HarperCollins books can download discounted ebook versions from the publisher's website. It's a fantastic idea, but I worry that the system is open to abuse.

What's to stop someone picking up a book in Waterstones, secretly writing their name in pencil, then rubbing it out once they've nabbed a free ebook? The founders tell me they've got this covered: the app will be able to tell the difference between pen and graphite, and some claims get sent for human validation. I predict a surge in demand for ink erasers.