Room Recess
This site has many educational games in all subjects.
www.roomrecess.com
Sheppard Software
This site has an abundance of fun, educational games ... including the European and South American country games the kids enjoyed playing so much in the computer lab!
http://www.sheppardsoftware.com
Free Rice
Play a vocabulary game and help feed third-world countries! For each correct word guessed, grains of rice are donated to third-world countries through the United Nations.
http://www.freerice.com
Fun Brain
This site is a great resource for educational games!
http://www.funbrain.com
School Time
Fun and educational games in every subject!
http://www.schooltimegames.com/