I develop www.BuzzMath.com (currently in Beta), you could try to create a free account. Feedback's welcome!
It's for middle school, students can exchange ideas but can't copy (it generates an infinity of possible numbers and solutions per problem), and it's very very beautiful :-)
Feel free to have your school link to my site. I've got 100+ interactive math activities bookmarked. All the links are visual which makes it easy for the younger ones. Click on the link below and select "Math" from the main menu. Have fun!
Hi Norm. If I can put forward a plug for products that have been developed by teachers in our school district, NECTAR Foundation (www.nectar.ca) have a number of math and language arts programs for K-12.
If your school has a bit of money available, our school adopted SymphonyMath (www.symphonylearning.com). It is an excellent way to build number sense and beyond. We are using it K-2 but the program has up to 3rd grade skills. Some of our high school categorical students are using it as well. It has built-in leveling so it takes students up to the next level as they are able. See the scope and sequence at http://www.symphonylearning.com/symphonymath/scope-sequence/.
There are also some videos on the site that demonstrate the program.
As a teacher, I love it because I have a math center at the computers and I know that all students are working at their level and improving. It's also great because all teachers can log in and see student progress. I love this because I can easily check and see who's progressing and if they are spending enough time working. It also includes access at home because the software runs from an online server so the home program knows what they've accomplished at school and vice versa. So we sent the letter home to let our students practice there and the parents like that too.