How do you remove the bottom of a glass bottle?

I read this in a DYI magazine, but I have yet to try it. Sounds solid, though, but you must be very careful.

Take a piece of twine dipped in lighter fluid (or some similar accellerant) and tie it around the bottle where you want the bottom to break off. Being VERY careful, light the twine and allow it to burn for a bit. Then shock the bottle by dunking it in cold water. You should have a clean break right where the twine was.

Again, be very, very careful; this would not be the time to invoke your inner Steve-O. Or John Orr.