We bought the I-Pod nano for my daughter's birthday, along with a couple of cases so she could choose the one she wanted.
Despite being nowhere near the most expensive,This is by far the best, and the only one she uses. It fits perfectly, protects everything that needs to be protected, while still allowing the colour of the I-pod nano to be seen. Indeed, you wouldn't even know, without looking closely, that it was in a case at all. Because of the snug fit, it doesn't make the I-pod nano any larger than it needs to be.