I grew up with these cool emergency lights in our house; they were plug-in nightlights that essentially turned into flashlights whenever the power went out or you unplugged them. Handy to have around in the event of an emergency, or—if you were me—very handy to have so as to read a book after bedtime. (Sorry, Mom!)
As an adult I have tried to find something similar on the cheap for years; every inexpensive no-name brand I’ve tried has died within weeks and been useless. But today Buy.com has the Energizer Light on Demand Center for just $9 shipped, and it’s a trusted name and a decent price. (Comparison: Though it’s currently defaulting to the Buy.com option, Amazon’s regular price is $28.)
Plug it in, and it’s a regular darkness-sensing nightlight. Lose power, and it turns into an area light. Lift out the “stick” and you’ve got a long-life flashlight.
I’d say that’s perfect for keeping monsters away and finishing that book after hours.