April 8, 2008
Reasonable Basic Algebra by Alain Schremmer is available under the GNU Free Documentation License (GFDL). Chapters are available for download separately, or as a single PDF (18.4mb). Alain also has other texts in development at his site, Free Math Texts.
Update 2009-11-14: Link corrections done to fix errors. Update 2008-04-16: After contacting Alain, he’s told me that the source material for the textbook is also available. He also said its worth noting that the text is part of a “package including homeworks, tests, exams, etc.” and that it is “a standalone version of part of what is to be a three semester volume text, starting with arithmetic and ending with differential calculus”. We’ll certainly look forward to seeing this develop!