Film canister, or prescription bottle, filled with wood camping matches (strike when wet) and a striker sheet.
As you can see from my avatar, most of my camping is done on motorcycle trips - and part of my moto pack is a 1-liter MSR fuel bottle full of unleaded, in case my reserve tank goes dry before I get to the next gas station. Might not get me there...but it gets me about 18 miles closer! Also works well for lighting up wet wood
If you need a good heat supply , take a small metal coffee can , place a roll of toilet paper in it , then pour rubbing alcohol in it. Light it and it will burn a long time. If you want to put the fire out , just put the lid on .