Adding a temperature controller to your slow cooker

This is the one I have:
http://freshmealssolutions.com/store/products/-SousVideMagic-1500D-HD-sous-vide-controller-.html

This one costs $170 (I think I got mine a bit cheaper a couple of years ago). You can certainly make your own if you're handy. I made a built in one for my espresso machine, but I just bought this one for everything else because by the time I bought all the parts I wouldn't have saved that much and it wouldn't look as good.

Although relatively expensive, it really expands the capabilities of a slow cooker. I also use it with an 18 qt roaster for larger jobs, but most of the time I use it with my 7qt crock pot. A standard slow cooker has no thermostat. Instead the cooker just cooks at a set wattage which is usually adjustable with a switch that lowers the wattage. This gives you a little versatility, but not much. The controller gives you precise temperature control (usually within 1 or 2 degrees F). Add to this a vacuum sealer like the Foodsaver and you have a sous vide setup which allows you to cook meats and vegetables extremely precisely.

1. Just about any kind of meats or vegetables can be cooked this way from spare ribs to brisket to turkey legs or whatever else you can fit into a foodsaver bag.
   
2. Soft boiled eggs can be cooked very precisely with runny to custard like yolks however you like.
   
3. Pasteurize your own eggs in the shell (or beer, wine, etc.)
   
4. Make homemade yogurt several quarts at a time if you like.
   
5. An 18 qt electric roaster becomes everything from a proofing oven controllable to +-2F to a 15 qt water bath for multiple sous vide packs of food controllable to the same standard.
   
6. Throw a frozen steak in when you go to work and when you get home it's cooked rare to well done, or anything in between precisely as you like it all the way through the meat.
   
7. Cheap steaks are rendered tender as filet mignon.
   

I have a 4qt crock, a 7qt crock, and the 18qt roaster that this one controller works with making it a true multitasker. It also works with rice cookers.