I use the collapsible sunshade sold at Target and other places. They are packaged as a pair (get the kind that are two separate shades). With just a little manipulation it fits wonderfully in the sunroof. I have a 9 year old daughter and dog and they are now as cool as cucumbers during the day.
This is what we use in our Element. It's a roll-up tint. It has a limo tint shade to it and is pretty dark. Very easy to use. It's on suction cups. I'm AZ and it has never fallen off at all even at 118+ degrees outside.