Other
Cavalcade O'chemistry: Chemistry: The Awesomest Science
A free online textbook written by a chemistry teacher trying to create a better chemistry textbook. Site also includes tutorials and worksheets for students. Teachers will also find a teacher resource center that compliments the textbook.
CK-12 Foundation
Ck 12: Chemistry for High School
This digital textbook covers core chemistry concepts and includes interactive features, real-world examples, and videos.