Academic Employment Network
The K-12 job listing is limited, but it is a start.
http://www.academploy.com/

Educational Placement Service
Provides private placement (no charge) for teachers, specialists, and administrators. Serves educators and educational institutions-public, private, parochial schools, and college).
http://www.educatorjobs.com/index.phtml

ISM Career Corner
Several international administrative and teaching locators are listed toward the bottom of the screen.
http://www.isminc.com/index.php3?M=mmmpo

K-12jobs.com
K-12jobs.com concentrates on posting job opportunities available at kindergarten, elementary schools, junior high, high schools, and vocational schools.
http://www.k12jobs.com/

NationJob Network - Education Jobs Page
This site lists hundreds of education/teaching/child-care openings.
http://www.nationjob.com/education/

The Ohio Association of Secondary School Administrators
Administrative job listings (e.g., principal, assistant principal, superintendent, athletic director, adult education director, etc.).
http://www.oassa.org

Ohio Department of Education
The ODE lists administrative and teaching postions available in Ohio school districts.
http://www.ode.state.oh.us/jobs/

Teach for America
This organization recruits college graduates of all majors to teach for two years in under-resourced urban and rural public schools.
http://www.tfanetwork.org/tfa2/join_our_corps/home.asp