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