I may have mentioned before I love reading, and I'm keeping track of all my books past, present and future, on Goodreads (oh hey, friend me on Goodreads!)
As a child I would read everywhere; whilst eating; when watching TV; as I was walking; Whilst getting dressed; in the car; up trees and even in the shower (it helps to have long arms for that one), but even for a seasoned compulsive reader it is really quite difficult to hold a paperback book and knit at the same time. And, believe me, I have tried.
So I looked into book holders, and noted down several different designs as being of interest. I eventually decided on the Paperbax, not the cheapest but certainly not the most expensive, and with a very utilitarian approach to the problem. There is a rigid shelf from the center of which two spring-loaded arms are attached and these hold the pages back for you. Both the arms and the shelf have a rubberised back to them, so there isn't any slipping. Should you want the book to be free-standing, as in the photo, there are fold out wingy things on the back.
It's very simple but it works really well, and so far even the 737 pages of Sherlock Holmes didn't present it a problem.
I love this thing. Love it.