Links

StarFall: Interactive comprehension and phonemic activites for young readers.
TRAILS: Tools for Real Time Assessment of Informatin Literacy Skills
FreeReading: A free reading intervention site geared towards students grade K-3 complete with literacy activities and lessons/ideas links. 
ReadKiddoRead.com is a user-friendly site designed to help parents, teachers, librarians, and other adults find books that kids of all ages will enjoy.
Online Interactive Stories for Kids: Talking books
Links to Tons of Reading Sites for Students
Tar Heel Reader - Books for beginning readers of all ages - students can create and "publish" their own books
 
Fun Sites
Science
Foss Web
Ice Stories- Dispatches from Polar Scientists
Interactive Science Simulations: Might be higher than Elementary Level but you have to check out the Simulation under Electricity, Magnets & Circuts called the John Travoltage.
Cells Alive: An Interactive Animation of Plant and Animal Cells
Your Bones
The Visible Body: 3D Human Anatomy...AMAZING SITE!

Social Studies
SHOW/World: Choose a subject and watch the globe change based on data
Frontier Alaska Game: Think you've got what it takes to survive in the Alaska Wilderness?

Museum Box: This site provides the tools for you to build up an argument or description of an event, person or historical period by placing items in a virtual box.