User Review: Therm-a-Rest NeoAir
It is comfortable, light and easy to pack and fit into your pack. On the downside the material it is made out of is noisy. You don't notice it as bad with a sleeping bag.
I bought the pad for my daughter and she is 6 so it is perfect. It is so small and light it doesn't add much weight to her pack, and being a kid she sleeps sound enough she never notices the noise.