i've read of using burning string to cut a bottle by quenching it after flaming it
http://users.ticnet.com/mikefirth/bottle.htmreadymade magazine had this recipe:
Ingredients:
+ glass bottle
+ large bucket full of cold water
+ kerosene or lighter fluid
Tools:
+ cotton string, roughly the thickness of yarn
+ matches or lighter
+ protective goggles
+ wooden spoon
+ work gloves
+ emery paper
1. Fill bucket with cold water at least as deep as the bottle.
2. Dip a piece of cotton string in the kerosene and squeese it until it no longer drips.
3. Tie the string tightly around the jug.
4. Put on the goggles and light the string in several places.
5. Immediately when the string has finished burning, submerge the bottle in the cold water.
6. Remove the bottle and tap away the last pieces remaining with the wooden spoon.
7. Sand the bottom with the emery paper until it's no longer sharp.
i would not try this on a full bottle though
unless you were trapped on an island with a case of wine