One of my favorite blogs, Open Culture, has just published a collection of more than one hundred free textbooks available online. The textbook collection can be found under the “textbooks” tab at the top of the Open Culture homepage. All of the books in the collection can be viewed for free and most can be downloaded for free. The titles in the collection are appropriate for high school and undergraduate use. The collection contains more mathematics and science texts than it does texts for the humanities.

Applications for Education
If you’re looking to replace the textbooks used in your classroom or you’re looking for supplemental texts, the Open Culture collection of free textbooks is a great place to start your search.

Here are some related items that may be of interest to you:
Seven Places to Find Free eBooks
Google Books Adds Shelving Options
Embedding Books Into Your Blogger Blog or Google Site