University of Pittsburg's "Big List of Resources", for Open Educational Resources, listed by Course and Subject. Has a mix of complete courses ready for use, Open Access textbooks, repositories, free multimedia, images, and artwork.
From the Resource page: "On this page, you will find some reasons to use OER in your classroom. On the tabs across the top of this guide, you can find resources for finding, creating, and researching the effects of OER."