Ever lie down in bed, realize the lights were still on, but you're too lazy to turn them off yourself?
Well in minecraft you probably just sleep with the light on anyway.
Well I was toying around with BUD switchs(Block update switches), and I can up with a pretty amusing idea. What if when you lie down in your bed, you wire your lights to a BUD switch so they go out on their own. And then, when you wake up, the switch trips again and turns the lights back on.
So I went out and spent a good two hours or so, toying with the idea and compacting it together. Throughout this process I can proudly say I've made my first real redstone contraption. I mean, I've rigged piston doors and whatnot before, but nothing beyond the very basics.
I used a block update switch that triggers when you sleep, and hooked it up to two very basic block switchers in my roof. I did set it up in such a way that the update detector could fail to reset on very rare occasion. This is because the totally safe way takes too long, and by the time it updates, it's morning and the lights are all still out.