What other web resources can you recommend?

My top 10 list of favorite web resources for teachers: 

1)The Exploratorium's Hands-On Activities 
2)RAFT (Resource Area for Teachers) 
3)Discovery School Lesson Plans 
4)Librarians' Internet Index 
5)Wikipedia 
6)The Science Spot 
7)How Stuff Works 
8)USGS Education 
9)The Science House 
10)The Best on the Web for Teachers