I was getting nervous about our 18 year old 15.2 cf Whirlpool freezer and I was getting real tired of defrosting it so I got a new 17.7 cf frost-free Whirlpool. After debating with myself over what to do with the old one, I decided to convert it to a refrigerator.
I bought an external Century Digital Cooling Thermostat Controller for $19 delivered. I also got a dual zone AcuRite Refrigerator / Freezer Wireless Digital Thermometer for $24 to make it easier to tame the thing and monitor performance of it now that it lives in an outdoor workshop room.
All in all, it works great. It only took a couple of days to get the settings dialed in to keep it at 37° F.  You have to find the right place to put the sensor to keep it at the temperature you want. When this thing is cooling to 37°, it burns less than 5¢ a day at our KWH rate. 
One drawback is it condenses moisture and drips from the upper coil. I thought I could help some of that with a quart sized calcium chloride moisture trap but they don't do very well at that low of a temperature. My workaround  is keep things sealed tightly or covered with 6 mil plastic sheet and leave the bottom drain open. I set it on 4x4's for enough altitude to direct the drain tube into a small flat pan underneath where condensate subsequently evaporates.
I'm not using it for much yet. So far just for storing a case of eggs for the dog food and thawing and brining big hunks of meat. I have a big ol' turkey in there preparing it for smoking this weekend. I may try dry aging some cheap brisket soon if I can find a huge one. The 75% humidity is just about right for that and for storing my pods before freezing or drying. The freezigerator also allows me to play with using the smaller kitchen refrigerator as a warmer "root cellar" for certain foods that do better at 55° than in the pantry. I'm happy with this contraption.
Edit: Another nice thing about the freezigerator is it takes only seconds to return it to duty as a freezer. Adds a lot of redundancy.