I have coded orientation-lock setting for GeeTasks. Since I didn't want you to have to go to Settings each time you needed the larger keyboard, I made it a little smarter than the name suggests:
When the "Orientation Lock" setting is Off the app behaves same as today - most places in the app (all but one, really) rotate the screen in response to changed device orientation.
When the setting is On, only one orientation is allowed for the entire app - the orientation that device was in when you started the app. More accurately, the reading is taken within 2 seconds after the app is started, so you have to hold it in the desired position for at least that long.
Thus if you opened up your shopping list in the store using single-hand-firendly portrait orientation, you can then walk down the isle with phone in hand without the app rotating back and forth on you. Or if you lay down in bed on your side you can keep the app interface parallel to your body, rather that controlled by gravity.
On the other hand if on a rare occasion you wanted to type something long that needs big keyboard you only need to tilt the phone before starting the app, and then the entire app is locked into landscape until you quit it.
I think the "Orientation Lock" setting should be great for casual users. Power users will probably prefer the ability to switch screen orientation on the fly.
I expect to release this in the next Beta within next couple of weeks.
Please post below what you think.