Sphere generator

This neat tool by Bram Lambrecht outputs instructions for a LEGO sphere in MLCad format. You can select size and whether you want to use jumper plates to make them more spherical or not. These are very useful in a variety of projects - they've been used as roofs, hot air balloons, and more. The sphere was originally designed by Bruce Lowell, and they're thus commonly known as Lowell Spheres.