It's the middle of the night, and you have to go to the bathroom. Sure, you can stumble to the bathroom in the dark, possibly hitting your shins or toes on anything on the floor or in the path between you and the bathroom door, but you don't want to blind yourself by turning on the light. The solution? Ground effect lighting for your bed!
Over at IKEA Hackers, they use a bed model commonly purchased at IKEA, but the trick can be applied to pretty much any bed with a flat underside that's lifted up from the ground a bit. Bonus: it looks really cool.
Pedro Farinha decided that he was tired of blinding and being blinded by his wife when one of them would get up in the middle of the night to feed their newborn baby.
With a little elbow grease, a kitchen-style fluorescent light, and some screws, he mounted the light on the wood bar on the underside of the bed and connected a switch to the light with enough wire that he could put the switch at the top of the bed. Now he or his wife could get up to change or feed the baby and go to the bathroom, with enough light to see but not so much that they'd wake the other person still asleep.
One of the best things about this tip is that it doesn't require anything IKEA really; a flexible strip-light or even a set of LED Christmas lights would work just as well as the fluorescent. Any bed that's up off the floor high enough for the light to spread out from around the underside and that has a place you could mount or tie in the lights would work as well. Just make sure to clean the dust bunnies out from under the bed first and make sure the light you use doesn't generate any heat (like incandescent Christmas lights or bulbs) – you don't want to inadvertently create a fire hazard.
Light in Malm Bed [IKEA Hackers]