ABCya.com is a a great resource for elementary computer and classroom teachers to have. I used this Web site a lot when I introduced the Internet to young children. It is very easy to navigate and teaches children how to use the forward and back button as well as the "X" that closes out a window. More importantly it is a great way to reinforce mouse manipulation- and it's fun!
Great Resources for Computer Education:
Kindergarten - 2nd Grade
3rd - 5th Grade
Aside that, ABCya.com offers educational games in language arts and math. From ABCya.com "All children's educational computer activities were created or approved by certified school teachers. All educational games are free and are modeled from primary grade lessons and enhanced to provide an interactive way for children to learn."
I strongly suggest this site for both computer labs and elementary classrooms.
Disclosure: I was not paid to state my opinions and they are 100% my own.