Here's an open source effort to design a low cost (both assembly and maintenance) tractor called the LifeTrac. Key attachments: backhoe and well drilling. It uses modular design for versatility of use and low cost repair.
The "Open Source Ecology" wiki (of which this design is a part of) is yet another example of the many efforts underway to accelerate DIY technology development for Resilient Communities (The RC). As personal fabrication improves, these tinkering efforts will become MUCH more sophisticated at an ever decreasing cost. We (collectively, those of us engaged in decentralized thinking/action) are in the process of reinventing how the global economy is structured at a root level -- good thing we didn't ask permission.
Here's an archive for Resilient Community posts.