http://www.starfall.com/ - a great learning to read website. My kids love it, and my 2 year old recognizes all of his letters and the sound each one makes.
http://www.tuxpaint.org/ - this is a fantastic program you download onto your computer for free. You paint with the mouse, and there are also "stamps" you can change the size and color of, "magic" things you can do to the things you have painted, and even typing words. I admit, I have played with this one while the kids are asleep!
http://www.playkidsgames.com/games/turtle/ - this one is a memory game that challenges my 5 year old. He loves helping the turtle cross the finish line.
http://atv.disney.go.com/playhouse/music/ - Playhouse Disney has a game called Pluto's Musical Maze. It introduces children to musical instruments and the sounds they make.
http://pbskids.org/ - More learning and activities based on the PBS kids' shows.
http://www.nickjr.com/index.jhtml - Nick Jr. has some fun printouts and activities for kids.
http://www.noggin.com/index.php?home=0 - Noggin is an offshoot of Nick Jr. They have good learning activities on their website.
http://www.sesameworkshop.org/sesamestreet/ - The Sesame Street website. Sesame Street also has podcasts available on iTunes to download for free that my kids love.
Chateau Meddybemps--funny name, charming website
Suessville - Let your child loose on a site about Suess!
Our goal is to have a continually updated list so you can check back often and see if there are any new websites to check out. But that means we need your help in updating the list. So, if you have other websites your kids enjoy, please put them in the comments and we will be sure to add them to the list!