With paper books, I don't go shopping that much, and I usually can't start reading right away. So I buy plenty of books that I never get around to reading, or I intend to read books and I never get around to reading them.
But with iBooks (the e-reading solution I'm using), I can decide "I've got some free time, and I'd like to read
I still don't have a good solution to the problem "I'd like to read something; what shall I read?" But this particular convenience of the e-book has gotten me to read more.