Here in Au the sun is sooo strong that many people like to just add a blanket too, but if the child is older and they want to see out, they won't like it.
Here is a web site I found that sells different stroller shades.
http://www.strollersunshades.ca/index.php
I have a Valco one that I use on my jogger and it folds up really small. You can buy them in the states. It is called the Universal sunshade for 3 wheeler, but it fits the peg. My friend here uses this on her peg.
http://www.valcobaby.com/2006/accessories.htm
I just tried it on my peg and it fits, here are some pics of it.
It has 2 ways to use the shade, for dark coverage if sleeping a black piece of material comes down and if they are awake and just needs sun protection then you can roll the black piece up and snap it into place.
I just previewed my post and my pics did not resize small? Sorry
I hope this helps!