When your Nook sleeps or is sent to sleep your normal portrait screensaver appears rotated, squished and with black borders.
Clearly, the Nook developers never anticipated that people would be using landscape mode.
I have a mod to /system/framework/services.jar to fix this.
If the graphic is either 600 x 800 or 800 x 600 it will put it in the orientation that fits.
If the graphic is 800 x 800 it will put it in the current orientation, centered at a scale of 1:1.
Since a lot of people seem to use a moded system.jar already it would have to be integrated in.
Is there interest in this?