Buy a book from Apress (such as the superb Definitive Guide to Django ) and you can get the PDF version for a fiver , so you can keep a copy on your laptop when you are on the road. What a great idea. I don’t want only the PDF - I much prefer to read the dead tree edition. But you can’t carry dozens of chunky tech books around with you, so I want the PDF too. Clearly I shouldn’t have to pay full whack twice, but the fiver that Apress is asking seems fair. I wish O’Reilly did this.