http://oswego.org/ocsd-web/games/mathmagician/cathymath.html  This one is fun for timed drill practice.  You can even print out a certificate.   NEW! 

http://www.harcourtschool.com/activity/thats_a_fact/english_K_3.html  I like this one for computation practice as well.  NEW!

http://www.mathplayground.com/MathHoops_Z1.html   Here is a great site for practicing word problems.  NEW!

http://www.rccsd.org/MSmith/Math.htm You will find an amazing number of resources on this third grade site   NEW!

http://www.coolmath4kids.com   Click on mathgames and then arithmattack.

http://www.Superkids.com/aweb/tools This one is  also great for home made worksheets.

http://www,Aplusmath.com/games/index.html  I love this one - so much to do!

http://www.mathcats.com/sitemap.html  You will have so many choices here. Try clicking on multiplication and division and you'll have many activities from which to choose - I like the interactive multiplication table and the multiplication grid.