The Art and Science of Leadership
http://www.nwlink.com/~donclark/leader/leader.html
This site offers an introductory leadership guide aimed at new supervisors, managers, or any individual that has aspirations to be a leader.

Center for Creative Leadership
http://www.ccl.org
This site provides a variety of resources that focus on understanding and expanding the leadership capabilities of individuals and organizations in public, private, nonprofit, government and education sectors. Their mission is broadly focused on leadership development for the benefit of societies around the globe. Many resources (e.g., workshops, books) must be purchased but some excerots and articles are available at no cost.

Facilitative Leadership: The Imperative for Change (1992)
Southwest Educational Development Laboratory (SEDL)
http://www.sedl.org/change/facilitate/
SEDL is a not-for-profit education research and development corporation. It creates and provides research-based products and services to improve teaching and learning. Facilitative Leadership is a guide for successful leadership strategies that is focused on promoting successful change in school settings.

Greenleaf Center for Servant-Leadership
http://www.greenleaf.org/
This site is sponsored by a not-for-profit organization and aims to seeks to build an international network of those interested in the study and application of servant leadership. Information on the site is aimed at helping "people understand the principles and practices of servant-leadership." Many publications on servant leadership are available for purchase but some information is available at no cost.

National Network for Social Work Managers
http://www.socialworkmanager.org
This site The National Network for Social Work Managers is dedicated to equipping people-centered leaders. The Network began in 1985 and was incorporated in 1987. In the Network's ongoing efforts to address the needs of social work managers, and to inform the profession and other interested parties of the unique skills of social work managers, a set of practice standards has been developed.  These are not minimum standards, but rather are descriptions of the level of practice that is expected of experienced and academically trained professionals. The list of standards and competencies can be viewed at this site.