Interactive Games k-5 - Great websites organized by grade and subject from Cedargrove School district.
FunBrain.com - Math, reading, interactives, and lesson plans. K-3
Mrs. Cannon's Computer Lab - Great site with lots of interactives. Don't miss the link to other months for additional help!
Kinder Site - Nice list of interactives for ages 3-7.
Oak Street Elementary - Lots of interactive sites organized by grade level and subject.
Math Websites created by the Oswego Schools - Includes Power Lines, plus a game maker.
Geometry Interactives from HomeSchool Math!
Shodor Math Interactives - Great site for 3-4. Lots of Middle School/High School as well.
National Library of Virtual Manipulatives - Great site for k-4, organized by Numbers, Algebra, Geometry, Measurement, & Data Analysis & Probablility
Internet4Classrooms - Lots of online games organized by grade and subject.