I've mentioned this tool to a few people before, but I figure I may as well post about it here. The Minecraft Structure Planner lets you plan out structures you want to make in Minecraft and preview the result in 3D. This is very useful for making complex structures or statues and the like, since you can adjust the shape and make changes quickly when something doesn't look right. It also tells you how much of each material you'll need for your construction. There's also some algorithm-generated structures like spheres, mazes and the like, if you're into that sort of thing.
You can find the tool here:
http://minecraftstructureplanner.com/

