This is certainly not an exhaustive list of math resources, but there are some excellent lists of lists, lesson plan sites, and some award-winning Web pages. This is a searchable database with information on projects, resources, and organizations devoted to reforming K-12 science and math education. Dozens of sites for students and teachers. Includes categories for subtraction, fractions, decimals, multiplication, and place value. Most of the AIMS publications are available from the Heartland AEA Professional Library.
Activities use everyday items.