We use RightStart math and love it. It is a wonderful curriculum that incorporates many games, fun games, fun MATH games. My kids enjoy playing them and don't realize they are learning....cue evil laughter. If you don't use RightStart, but want to play more math games, they have a book of just games (Math Card Games) I would recommend you purchase it as it has fantastic games that I won't describe here. You can also purchase the "kit" which has the book and the cards needed to play.
We also enjoy these math games:
1. Money Bags - I hadn't taught "money" to my 6-yr-old when we started playing this, but he can play easily now. We played this today and I totally lost...even the 4-yr-old beat me and he spent most of the time knocking other people's "guys" off the board and stealing money from the bank.
2. Sum Swamp - a great game to practice addition and subtraction. The 6-yr-old can play and so can the 4-yr-old with some help. My 10 and 9 year olds are almost too old for this, but they still want in on the action.
3. 4-Way Countdown - you can add, subtract, multiply or divide so it works well for kids of all ages. My only complaint is that it has only 4 players. Sometimes I want to play too (okay, all the time) and with 4 kids I'm always the odd man out.
4. War - yes, good old war. We play it many different ways. When they are little it's the traditional "highest" card wins. Or lowest card. We also do addition war where you play two cards and add them up; the highest total wins. Or subtraction war; play 2 cards and lowest score wins. We typically use the number cards from RightStart because they go from 0 to 10 and I don't have to try to explain queens, kings and jacks, but you can play with whatever you have.
I've thought about getting Presto Change-O. Any other games I should check out????