Open Educational Resources are freely accessible educational resources that can be used, re-mixed, and altered for educational purposes. They can include full courses, parts of courses, videos, handouts, tutorials, etc...
The Open Education Consortium is a global, non-profit consortium of educational institutions that advocates for global open education. Its website includes news and information on recent initiatives.
SPARC is another global coalition that advocates for open education, open access, and open data. Its website includes background information on open initiatives as well as news on recent legislation.
U.S. government works are not restricted by copyright, and there are many resources that may be useful for instructors.