Make unique lamps and vases from leftover bottles by following the instructions posted here.

Method 1: Dip a piece of common string in alcohol and squeeze dry, or as dry as it will get without dripping. This string should then be placed on the already marked glass and tied tight. Light the string and let it burn off. Immediately, while the glass is still hot, plunge it into cold water. Be sure the container of water is large enough to let the glass to completely submerge, as well your arm up to the elbow, so as to deaden the vibration when you strike the glass.

Strike the glass with your other hand above the line using a wooden stick and hitting a sharp stroke. This quick, sharp stroke will break the glass where the burning string has weakened it, as if done by a regular glass cutter. This method may be used to cut bottles in any shape, and to make vases. You can perform many such cuttings on glass.

For more methods head over here.

DIY: lamps and vases from Bottles