Either A FlashLight, or a Lantern.
Having to place torches everywhere just gets tedious after you wasted your 3rd stack.
And I don't want any of that "Press f to use the Flashlight" shit. You have to hold it in your hand, I just find the "Press F to use FlashLight" stuff Annoying, and Immersion Breaking.
PS : This thread's full of interesting ideas, I'll give it that.
@A Raging Emo : Notch has confirmed about adding NPC villages, you can chat with the NPCs, or make them your servant bitches. He's not went into much detail.