I agree with the parallel universe theory. I don't know if one is happening in the future relative to the other or if they're truly parallel. I think there's some truth the theory that the Losties figure out the parallel thing when they die. Between Juliette and Charlie that seems at least possible if not probable.

When Sayid came back to life, I could have sworn it wasn't his voice that spoke but my wife thought his voice was just gravelly from having just drowned.

I'd say both Jacub and his nemesis are supernatural in some way or another. One can't kill the other and they seem to ahve some pretty crazy powers. I've always thought they represented the battle between good and evil though who's which is anyone's guess.

Why does Jack seem to remember the island after they reset when the others don't? Is that just me?