A technique that has not been mentioned (but it works only for Champagne, apparently) is to open it with a saber. A heavy knife will also work.
The bottle is held in the left hand, and the saber wielded with the right hand: the saber slides along the neck of the bottle and hits with its flat the place where the bottle seam joins the thicker (and last) part of the neck.
If done properly, the high pressure inside the bottle will crack cleanly the glass, and the top of bottle (cork and all) will fly away.
Notice that the bottle will be left with a very sharp edge. Notice also that if the bottle cracks in your hands and jugulates you, it is all your fault.