This is probably one of the best things I have seen in a long time: the global village construction set. This is a set of 40 machines that you can use to establish an entire village, but what is so special about that? The group has researched all the tools you would need to establish a village, designed them from the ground up to cost 8 times less than commercial versions and give the plans (with videos, cost sheets, schematics, materials lists, etc) for free! The entire project is open sources and they have released and prototyped 8 of the 40 machines already.
One machine that is really interesting is rammed earth press which a few people can press enough bricks in a day to build a small house! See all the machines here