How to improve slum-dwellers' life conditions with a blog! The $300 house was first described in a Harvard Business Review blog post by VIjay Govindarajan and Christian Sarkar. It is now becoming a reality through actual financing.
The original blog: http://blogs.hbr.org/govindarajan/2010/08/the-300-house-a-hands-on-lab-f.html
The venture: http://www.300house.com/about.html