I have been teaching gifted students in grades K-5 for the past three years.  Below are some of the links I have found both useful and informative:

Pennsylvania Association for Gifted Education

Naeg Center for Gifted :  This site, supported by the University of Connecticut, includes research as well as the school wide enrichment model advocated by Renzulli.

Hoagies Gifted Education :  This site includes information for educators and parents.  Lots of articles, research, and resources!

Center for Gifted Education:  College of William and Mary.

Websites for Teachers:

A Different Place:  Gifted Classroom Website - Nancy Bosch

A Not So Different Place:  A blog about gifted students by Nancy Bosch 

Cybrary Man:   

Frederick County Public Schools



Mr. Mahoney's Classroom:  Lots of links for teachers

Mrs. Sunda's Gifted Resources:  A gifted teacher's website

Web Encounters of the Gifted Kind

Ingeniosus 

Other:

How Stuff Works:  Ever wonder how or why something works?  Check out some cool information at this site. 

Google Sketchup:  A free download from google.  Create unbelievable 2-D and 3-D drawings.

John Hopkins Center for Talented Youth:  Summer programs and more for gifted students.


C-MITES:  A program run by Carnegie Mellon that provides testing and programs for gifted students.