Open Textbook Initiative. The The American Institute of Mathematics (AIM) has developed evaluation criteria to identify the open source textbooks that are suitable for use in traditional university courses. The Editorial Board maintains a list of approved textbooks which have been judged to meet these criteria.
UTMOST: Undergraduate Teaching in Mathematics with Open Software and Textbooks. The UTMOST project is an NSF IUSE grant focusing how students understand and faculty actually use textbooks in undergraduate mathematics courses. UTMOST will use this understanding to produce textbooks that are more effective in promoting student learning. The major components of the project involve education research, resource development, dissemination, and evaluation.
MathBook XML is a lightweight XML application for authors of scientific articles, textbooks and monographs that incorporates the best of DocBook, LaTeX, and HTML. When a document is written in MathBook XML, it is possible to quickly produce print, PDF, web, EPUB, Sage Notebooks, and iPython Notebooks from a single source.