I learned a lot about construction during my stint as a Peace Corps volunteer on the outskirts of Sao Paulo, Brazil. The first project I worked on helped folks build some simple homes in a "self help" housing program. When that project came to an end, I organized some classes in basic construction skills and literacy.
The "volunteer bug" continued back in the States and I have had the pleasure of working with a number of housing related organizations.
Working with such volunteer organization can be frustrating: the needs are always greater than the available resources and the problems always more complex than envisioned at the start. But such work is always rewarding. And for me some of the greatest rewards have come in the people I have met in the process of such work. These people have become some of my very best friends.
So here is a list of some organizations which have impressed me over the years and need your support. Check them out, donate some time and/or money and tell your friends about them. I would be happy to accept some of your suggestions for this list.