Links to free resources/textbooks that are on the web
cK-12

This is probably the most comprehensive site I know about where free textbook-like content is available.  The nice thing about this site is that everything is broken down by chapter so you don’t have to scan through the whole textbook.  You can actually piece together your own textbook by pulling chapters from several places.

http://www.ck12.org

Hippocampus

This site mainly has upper level high school course resources however, they do have Algebra I resources that include narrated tutorials and the ability to link to several textbooks.

http://www.hippocampus.org/

epubBooks

This is a site where you can download books to read for free to ereader devices.

http://www.epubbooks.com/