Sliding row and word markers.
I use the iOS platform mostly... but it would surely come in handy, while reading and when returning to the app after closing it, a sliding row marker. There's an app called KnitCompanion that has this feature. They call it sliding row and stich markers. This allows you to close the app, come back at any time and you will start right were you left off last time. You never loose you place. Plus, you never have to reread to find your place as this sliding marker will guide your eyes through the reading, even after taking your eyes off the screen for a minute. Thank you!