Curriculum Materials
National Council of Teachers of Mathematics (NCTM)
NCTM Illuminations Website provides resources with interactive tools to illustrate curricular and pedagogical ideas in the Principles and Standards for School Mathematics.
Visit the sections on Tools and Lessons for illustration and analysis of teaching ideas

National Curriculum for England
Curriculum Online  
Download National Curriculum Booklets

Standards website of the Department for Education and Skills (DfES)
Find support packages in the sections of "Framework" and "Resources & Publications"
Framework for Teaching Mathematics: Years 7,8 and 9
Other major sections related to Mathematics

Qualification and Curriculum Authority (QCA) maintains and develops the National Curriculum and associated assessments in UK.

Mathematics Learning and Teaching Initiative (MALATI) is a curriculum project of the Open Society Foundation for South Africa.

Discussions about Mathematics Curricula
Mathematically Sane: Promoting the rational reform of mathematics education  
Mathematically Correct  
Reflecting on Sputnik: Linking the Past, Present, and Future of Educational Reform