Hearts, tongue, and liver are what I consume regularly.
The trick for heart and liver is to not over cook them. Overcooking heart makes it very tough and destroys all the taurine in it. Liver takes on a very nasty smell.
I use this recipe and make a pate out of both: http://farmlet.co.nz/?p=199 I soak the liver in water, which I change a few times before cooking it - this seems to get rid of the smell. Also remove any silver skin off it before cooking as these tend to be stringy.
Again, just lightly cook the heart and liver chunks, just for about a minute or two.
The result is very creamy, has an almost cheese like flavor. I then take this and place it in a pyrex bowl, cover it with cracked pepper and let it cool, then place it in the freezer. I then hack off a chunk of it and put it in my lunch, which is usually a salad. Since it's frozen, it helps keep the salad fresh, and by the time I eat it, it's melted and ready.
Tongue you can make the same way as corned beef, but remove the skin after it's cooked. As per Cordain tongue is similar in nutrients to brain, and these days there's a fear of CJD from brain tissue, so if you have it, make sure it's not beef, sheep, or other animals that are susceptible to it. I tend to avoid beef ox tails for the same reason since they do contain some nerve tissue. (I get most of the organ meats from Bison which seems to avoid the whole issue.)
While not organs, beef tendons are awesome when making a brother - add them in towards the end unless you want them to dissolve.