We have made this quite a bit for special occasions - Christmas and the like.  The thing you should know is that you don't get a ton of meat (so you may need 2) and it makes a lot of duck fat - good for chips.

Duck' L'Orange

Ingredients

2 ducks (around here they sell "ducklings" around 3 lbs or so)
2oz (60 g) butter or oil
salt and pepper

The sauce
2 orange
2T sugar
4t vinegar
4 cups water
4 chicken stock (bouillon) cubes
4t lemon juice
6t arrowroot or corn starch
1 cup sweet sherry
1/2 cup Grand Marnier
salt and pepper

Method

Roasting
1. Prepare stuffing if using [link].
(If in doubt, cut two or three oranges and fill the salted cavity with these.)

2. Preheat oven to 350 F.

3. Coat the duck with butter or oil and salt liberally then place ducks in baking dish. 
Picture
Scoop fat off the top.
4. Cook for 1 hour or so (it will go back in the oven for a bit longer once the sauce has been added).  Brush the ducks occasionally with juices from the pan.
The sauce
5. Cut rind from the oranges (use a vegetable peeler) and boil in the water for 3 minutes.

6. Place sugar, water, stock cubes, orange and lemon juice, and blanched orange peel into a pan and boil rapidly until sauce is reduced by around half.
7. Blend arrowroot or the corn starch with the sweet sherry then slowly add to simmering sauce to thicken it. 

8. Add salt and pepper then Grand Marnier - then divide the sauce into two parts.
9. Remove duck from oven and drain fat from pan (retain if keeping for later). Pour half the sauce over duck then return to oven for another 40 to 50 minutes, basting occasionally.

10. When duck is cooked and well glazed (and the juices run clear) remove from oven and drizzle a little of the remaining sauce over the duck. Once carved, drizzle more sauce over the cut parts and meat.