From the Store description:
Night Stand Clock transforms your Phone into a most beautiflul home and away smart clock. This is the best designed alarm clock in the Windows Phone Store. Choose from ten stunning themes the clock like you prefer!
-Background Alarms with build-in alarm sounds
-Slide/flick up and down to dim the screen
-Local Weather forecast
Of course, as you'll have spotted from the photo above, there's a bit of an issue in Windows Phone's insistence on lighting up the capacitive control keys on the Lumia 930 - in a dark bedroom these can be annoying. This is a similar issue to that which I ranted about here.
That aside, the application does work - it disables the usual Windows Phone screen timeout, and so stays active all the time - which is partly why you have to have the 930 plugged into a charger of some kind.
The brightness of the display can be adjusted in very fine increments - to avoid AMOLED screen burn-in, it's best to keep it right down, but a swipe up the screen toggles on a fuller brightness temporarily, if needed.
So, not a perfect solution, but still one worth noting for Lumia 930 (and possibly 735) owners.