K-12 Jobspot - Search through hundreds of listings for teaching jobs. There's a "search by state" feature to help you find jobs close to home.
School Spring - This is one of my favorites teaching job sites. Access tens of thousands of job openings across the USA and worldwide. It's one of the biggest and most comprehensive teaching job sites out there - and they specialize in the field of education.
Teachers.net is a terrific forum for posting about anything related to teaching. There are many chatboards for job hunters.
Glassdoor - research almost any large company or school district. This is a great resource for learning about a company's work culture, benefits, and salaries.
Top Education Websites - features an annotated list of 100 educational (and fun!) websites and resources for K-12 students.
Monster - This is one of the top sites for matching job seekers with employers.