Lots of good math center games for the young ones. Yahtzee - "This game is so funny to see how excited the kids get. All they have to do is roll 2 dice and cross out the sum. They keep going until they have crossed out all of the numbers.
prince & co.: The Trading Game: Money Style.Race to a Quarter. This game is VERY simple but powerful for the kids because it helps them to make those connections that 5 pennies = 1 nickel, 2 nickels = 1 dime, etc.
Here's a nice post on using place value cards to help students understand decomposing numbers and expanded form. Includes a link to a set of place value cards. Could change colors to go with Math-U-See.
Math tub idea: Get two ice trays from the dollar spot at Target, write numbers on white labels for each hole, and kids toss a cube in each tray and add numbers together on recording sheet or whiteboard. You could also do 2 digit by 2 digit multiplication.
Make Your Own Math Games: Egg-O! -- Hands-on math games are a great way to add variety to your child’s education…not to mention a fun way to practice math facts! Egg-O is a quick game you can use to practice addition, subtraction, or multiplication facts.