This article is about brainstorming about the best/cheapest ways to obtain shelter.
Getting a shelter can be done as simply as by looking for an old (empty) industrial building/complex and renting it (this may be done even in Europe for as little as 200$/month). Such large buildings may be shared by an entire group of fellow room mates/co-payers.
In addition, complete abandoned villages may be usurped (dough this will require a fair amount of planning and is best done with a large group of decision-makers). It also allows other (poorer) people to be housed (eg in return for work provided).
Still usable (sturdy constructed) deserted towns (usually referred to as 'ghost towns') in Africa and abroad can be used to house refugees and poor people in Africa/developing world. Refugees (without much possession or any roofing) and coming from insecure parts (e.g. in Angola, Sudan, Chad, Central African Republic, DR Congo, ...) may be relocated to these towns in Africa/other continents to repopulate them and help out in the reforestation of the areas around the ghost town.
The reforestation programs may be conducted within Kyoto's Clean Development Mechanism-program to allow the projects to be self-sustaining (and perhaps even profitable). In addition, the ghost towns themselves can be fitted with the needed systems for life support using low-cost micro-generation and local food production system. Drinkable water and sanitation too may be produced on-site. More information on setting up off-the-grid homes may be found at Topic:Self-sufficiency and at the wikipedia
Even more information on decreasing the cost of the required systems can be found at an article I wrote. See this article at my website. Concrete villages which may be used in Africa include towns as
In regard to my second proposal on mapping out the abandoned villages, there is an extra suggestion I have to decrease the cost of the project. This approach would be the use of satellite imagery from Google Earth/Google Maps (which is easily and freely available online) to allow volunteers at home to spot the villages themselves and report/mark them (marking too may be done with Google Earth). When the images are not clear enough (e.g. when the village's structural state is unclear, ...) to definitely say whether or not certain items on the map are indeed abandoned villages, they may pass along the information to people on the ground (government-sponsored organisations, ...) to go check out the spot/GPS-location in question. Please take a look at the extra link provided about other projects that have been conducted in this way.