Solar (Vaccine) Refrigerator

Well, if you were looking for applications for the idea: Solar Vaccine Refrigerator, although they already have a low-cost solar collector in place. However, perhaps with the sunflower a higher-powered design is possible.

Either way, I'd think this tech is right up your alley.

Yeah, refrigeration is definitely going to need to be an application for this.

Absorption fridges seem fairly effective, and these guys seem to have a good one going without the need for concentrated solar, but not sure how home makable their rig is. Might need some reverse engineering...

I haven't looked into it properly, but other ways I know of to refrigerate; simple evaporative cooler, super easy to make but a little more complicated if you don't want to go through quite a bit of water. Or a Stirling motor driven in reverse, possibly by another Stirling motor / turbine etc. These can get things pretty cold, but not sure how well you have to build the Stirling(s) to make it effective. And a third option would be generate electricity and run a conventional fridge.
Anside from solar, there's some way you can cool using a combustible gas, like LPG or methane from a biodigestor. Campervans use them sometimes, but I'm not sure how they work. And while I think about it, rapid expansion of a compressed gas gets pretty cold too, so you could use a wind turbine to directly power an air pump, compress a cylinder, let the heat dissipate, and tap the gas for coolth.

And lastly, if you're looking to get things down to the ground temp (usually about 10-16 C):
http://urbangreenhouse.blogspot.com/2011_03_01_archive.html