Below are a few great web sites for curriculum integration across the curriculum at all grade levels.

Each of these sites has an ocean of resources for you to explore. 

Internet4Classrooms: Links for K-12 Teachers

Teachers First: Curriculum Links

Cyberbee: Curriculum Ideas

42Explore Thematic Pathfinder

Poway Curriculum Sites

Mrs. Gold's Class Curriculum Sites for Kids

Pike County Curriculum Websites