Check out the Weston A. Price web site - lots of info on organ meats, including a few recipes.
Their cookbook, "Nourishing Traditions" by Sally Fallon and Mary Enig is a treasure trove of recipes of this type (and many others). It's on Amazon.com.
And yes, they are nutritious - they're cheap due to the "ewww" factor. I can't even find this stuff at my local grocer - I have to order it from my CSA. But do read up on this, some of these organs may be too nutritious in large doses.