In rising occasions while shooting, I found that I need to know where the Nikon D90 CAM 1000 AF is actually focusing on (out of that 11 focus points) but there's no way to do that until the shutter release is re-engaged with auto focus sequence (release shutter release button and press it again to bring up those red/black focus boxes). It was a tedious task.
But while searching and playing with the menu (F2), I discovered you can actually set the "OK" button at the back of the camera to instantly highlight those AF points with a simple push of this button! Wow, with this set, tendencies of getting defocused subjects with prime lens dropped significantly for my case.
Try it as it gives Nikon D90 owners a stronger confidence while shooting with single-point prime lens.