I have one of these:
From crockpot. You can cook a 20lb turkey in it (unstuffed, can't use this with a stuffed bird). I did it a couple times. Comes out great! The meat falls off the bone.
This thing is good for any large cut of meat you want to slow cook. It doesn't heat up the house either.
One tip though, if you do cook a 20 lbs bird in it, check it about halfway through and remove some of the liquid, otherwise it can overflow.