Chart and Graph Generators - several sites that generate charts and graphs based on your data
Grade 2-3 math resources - This site has lots of activities for grades 2-3, including place value.
Math Playground - Computer based practice, worksheets, manipulatives and math games
eManipulatives - this site has several virtual manipulatives, including coins, counters, a neat number line and a hundred chart for multiplication. Great for a learning station or on the projector for the whole group.
Visual multiplication - This interactive multiplication table lets kids see multiplication visually.
Funbrain math arcade - Students select their grade level and play a variety of math games.
I4C 3rd grade Skill builders - A giant list of resources for math.
Rain Forest Maths - This site has hundreds of math activities, all arranged by grade level. Although it is not based on NC curriculum, many standards do overlap.