"This page lists resources relating to Everyday Math."
A bunch of interactive activities for all grade levels, but also separate pages for each grade level K-5 broken down by unit.
The National Library of Virtual Manipulatives now has an "enhanced" registration for teachers and classes that lets you use their structured lessons with the manipulatives, use saved lessons from other teachers, or edit or create your own lessons using their manipulatives. Students log in, and their work is saved for teachers to view! Lessons available (as manipulatives are also) range from K-12 (precalculus and trig are the highest level topics listed)