Solar cookers can also be used as a refrigerating device as well. Basically, by setting up the "cooker" at night so that the panels face the open (not trees, buildings, etc), it actually draws the heat out of the cooker rather than drawing it in. My research has indicated that this can actually make ice in non-freezing temperatures.
I've also began drawing up plans for one of these solar refrigerators. It is to be build very similar (albeit slightly modified) to the one in the link that MikeK posted. I plan on using a small freezer and building it like a box cooker, having it work at night. In the daytime, I will keep it closed to maintain the proper temperature. The freezer should be insulated enough to maintain the temperature, and it will be reopened at night.