For our formal math curriculum, we use Sunrise Math from Christian Light Education and LOVE it! But we incorporate lots of fun supplements and math games too. This week while playing our Sesame Street version of Chutes & Ladders, my kindergartner made the adorable comment that it was strange they called it Shoots & Ladders, because there weren't any guns in it. :D I explained the different spelling and, without us having a laundry chute, it wasn't easy giving an example. She simplified it by deciding we'll call it Slides & Ladders, which I concur makes it a lot more sensible and modern.
Here are just a few of our favorite free math sites where you can download worksheets, lesson plans, math games and activities.
KidZone free math printables
Math Worksheet Generator
Math in an everyday way: this site has simple ideas for incorporating math in your everyday life, at home, the grocery store, on the go and for the fun of it.
Also, sesamestreet.org has a ton of great counting games your toddler and preschooler will love!