Math Worksheet Wizard is another good site for free math worksheets for K-5. You can customize thousands of these worksheets based upon what you want to cover. The worksheets are attractive in a whimsical kind of way and every time you generate a worksheet, you get different randomly generated problems. What I liked about the kindergarten sheets was the option to use pictures, such as frogs, cows, kangaroos and koalas, instead of numbers. You have the option of black and white or color. This site is excellent for teachers, home schooling and just a good way to practice with your kids.
Some nice problems to use, especially for those with short attention spans who can get lost on a problem early on.
Love this site.