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.
Grade 2-3 math resources - This site has lots of activities for grades 2-3, including place value.
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.