We've been using the Mathematics Enhancement Programme (MEP) through the Center for Innovation in Mathematics Teaching (CIMT) with amazing success.
MEP is a math curriculum currently in use in British schools in the United Kingdom. MEP is free for non-profit use and while not specifically designed for home schoolers, the University Staff have been very kind to allow non-institutional teachers (home schoolers) access to their materials.
You can read more about MEP at their website:
Mathematics Enhancement Programme (Download Practice Books, Lesson Plans, etc. for free)
To enhance our kids' math experience with more manipulatives, I've added the Base Ten blocks.