If remembering to keep an emergency torch charged is beyond your responsible capabilities, here's a great tutorial on how to make another backup light source that never needs power or batteries. Over on Korea-based Hobby Design, there's a relatively simple step-by-step guide on how to make these glowing silicone light bulbs that should provide enough light to help you find your way around during a power outage.
The tutorial basically involves creating a plaster mould of an actual lightbulb, so that the final product can actually be screwed into existing sockets, as long as they're not plugged in. The hardest part is probably finding the luminous pigment needed to give the bulb its soft green glow, but that's nothing a quick Google search can't solve. [Hobby Design via designboom]