Candles. 6" diameter pillar candles and 9-hour UCO candles -- several dozen of them. And several UCO candle lanterns to put them in.

Flashlight/headlight-wise: Petzl e+lites which supposedly have a 35-45 hour run time, depending on whether it's on high and low. I have a few of these because they're so small and great for having in a purse, pockets, car, trailer... They run on two CR2302 lithium batteries.

http://www.rei.com/product/786024

I also have some small e-Gear LED lanterns which allegedly run 48-144 hours on four AA batteries.

http://www.essentialgear.com/store/p/153-Weekender-Lantern.html