The live cultures and lactic acid in yogurt helps marinate all types of meat. I use it to tenderize chicken (tandoori chicken recipe was enclosed by the earlier poster), leg of lamb, leg of goat and beef and chicken kabobs).
In order for yogurt to do its magic I recommend an overnight marination. The yogurt adds a very nice tangy touch to the finish dish and keeps the dish very moist.
Here is a leg of lamb recipe I make that uses a yogurt marinade:
Leg of lamb - trim all the fat
3 cups of plain yogurt (greek or middle eastern style is the best but Dannon will work)
Roasted and powdered spices - Corrainder, Cumin, Black Pepper - 3 tbsps
Red Chili powder - to your liking
juice of a 1 lemon
6 cloves of garlic minced
1 small stick of ginger minced
2 large Caramalized crispy onions. You slice the onion thinly and then fry the onions until they are golden brown and crisp, remove it and then crumble them with your hands.
1/2 cup of freshly chopped cilantro
1/2 cup of freshly chopped mint
Mix everything in the leg of lamb in an oven proof pan (foil ones work fine). Let it marinate overnight. In the morning, place the pan in the oven. Let it cook until the lamb is fully cooked.
Remove the leg and place it on a platter. Strain and reduce the cooking liquid until it's nice and thick. Pour it over the leg of lamb. Garnish with more freshly chopped cilantro, mint and slices of lemon and serve.