From: http://www.smart.net/~tak/haggis.html

The Dreaded Haggis (from Delia Smith's Complete Cookery Course)
1 sheep's stomach
1 sheep heart
1 sheep liver
1/2 lb suet, fresh (kidney leaf fat is preferred)
3/4 c oatmeal (most recipes say pinhead oatmeal)
1 ts salt
1/2 ts pepper
1/4 ts cayenne
1/2 ts nutmeg
3/4 c stock
Wash stomach well, rub with salt and rinse. Remove membranes and excess fat. Soak in cold salted water for several hours. Turn stomach inside out for stuffing.
Cover heart and liver with cold water, Bring to a boil, reduce heat, cover and simmer for 30 minutes. Chop heart and coarsely grate liver. Toast oatmeal in a skillet on top of the stove, stirring frequently, until golden. Combine all ingredients and mix well. Loosely pack mixture into stomach, about two-thirds full. Remember, oatmeal expands in cooking.

Press any air out of stomach and truss securely. Put into boiling water to cover. Simmer for 3 hours, uncovered, adding more water as needed to maintain water level. Prick stomach several times with a sharp needle when it begins to swell; this keeps the bag from bursting. Place on a hot platter, removing trussing strings. Serve with a spoon.

And a side of single malt, of course!