Practice reading, math and grammar at Fun Brain. And, parents, K and 1st teachers be sure to check out the cute games for the "6 and unders" in the Playground section. Fewer activities and a cleaner interface make this a user friendly alternative to Starfall.
Both English and Spanish versions of thematic stories and activities are available at Story Place. A variety of themes are offered each with a Topsy-Turvy Tale (students complete on-line), print-out activities, and suggested reading (pictures of the books make this very kid friendly).
Make graphs and charts at the National Library of Virtual Manipulatives. Notice how well organized the homepage is; it's a matrix on which you match the grade level with the skill and then click to retrieve a list of on-line graphing activities for students.
"At Switcheroo Zoo you can make new creatures, send postcards of your animals to friends, learn about animals, play games, watch movies, and much more!" During a habitat unit have students play the Build an Online Habitat Game.
Practice alphabetical order, synonym and antonym identification, sentence word order, and fact vs. fantasy at Game Goo. Scroll over characters to find out which game reinforces which skill.