I was doing some order of operations examples with the 7 year old today. It was good practice of multiplication, division, addition and subtraction and mental math. He really enjoyed it and I really enjoyed watching his mind work and how he plays around with different operations and math concepts in his mind and thinks out loud to get to the answer. It's really inspiring to watch someone enjoying the learning process.
Here are a few links that combine mathematical concepts with art and even some metaphysical thinking.
http://www.wholemovement.com/ - learning about the world, mathematics and art by folding circles. So in case you have an extra pack of paper plates handy and enjoy paper folding, this is a great site with a lot of circle art inspirations to keep one occupied for a nice long time(see the gallery).
http://www.stringartfun.com/ - a wonderful website with patterns and techniques, downloads and teaching ideas for making beautiful (and mathematical) string art.
Pinbroidery - a take off on the nail and string art, by applying these techniques to card making. Beautiful project ideas that could also be tied to mathematics.