Learning Box has wonderful base 10 block games that work well with your Promethean Board, Polyvision Board, or chalkboard. The first one practices making numbers between 1-999 using base 10 blocks. The student drags the blocks onto the mat, and when the correct number is made, the website cheers and the blocks dance around. (See picture above)
Learning box also has an estimation game with base 10 blocks. As you know, estimation is a difficult concept to teach to elementary school kids, but this is a nice way to show another strategy to master this concept.
Another base 10 block website to practice adding or subtracting numbers is from Arcytech. Even though the graphics are not as refined as the websites from Learning Box, this site has something that Learning Box does not: a hammer a glue bottle. Use the hammer to break apart a hundreds flat into ten rods, or use the glue bottle to glue them back together again. This lends itself to teaching addition and subtraction with regrouping. Check it out!