Firesteels... I don't even know why I'm so fascinated with them??
This was the first thing that came to my mind. I always toss a magnezium block and firesteel combo into my pack as an emergency resort thing. A few months ago I was camping near Mammoth in the low teens and my Bic lighter completely crapped out. If it wasn't for the firesteel to light my stove it would have made for a cold meal and a cold night (warmed water bottles). It is now one of the first things I grab.
Second would be the Petz Tikka headlamp that someone else mentioned.
