NCTM serves math teachers, math educators, and administrators by providing math resources and professional development opportunities. Working for more and better math for all students.
We used the National Library of Virtual Manipulative quite a bit in Math 120. This is a great resource for use with a Smart Board, in a computer lab, or with a few computers as a center. The activities are sorted by age group and Content Standard.
This mathematics forum website is a great resource for possible activity ideas to use with your students. The main page of this website includes six main link sections: numbers and operations, algebra, data analysis and probability, measurement, geometry, and other resources. Each of these subcategories has an array of possible topic areas and activities to go along with these areas. These activities are aligned with the NCTM standards and often include the use of manipulatives.