There are a number of websites that will provide teachers and parents with excellent information about gifted education.  Here are a few:

Academic Talent Search:  http://edweb.csus.edu/projects/ATS/

California Association for the Gifted:  http://www.cagifted.org/

Davidson Institute for Talent Develpment:  http://davidsongifted.org

GATE World: http://www.gtworld.org

Hoagies Gifted Education Page: http://www.hoagiesgifted.org

Khan Academy: http://www.khanacademy.org

Math is Fun: http://www.mathisfun.com

National Association for the Gifted:  http://www.nagc.org/