The Third World Development Online Library (CD3WD) is an open access collection of technical documents on appropriate technologies. Created by Alex Weir, the database has over 900 documents totaling more than 13 GB of information. More information and links for the project can be found at the CD3WD website. .
A full list of publications, with links to full text is available at the referenced website.
Some titles are also available on Appropedia at the CD3WD page.