How not to overcook anything. Just the facts. From Ina Garten. Great article on Yahoo Lifestyle. Click here for the whole article.
Baking
For baking, the tests are fairly straightforward and the same for almost all cakes. First, lightly press the rounded top of the cake. Does your finger make a mark or does the cake bounce back? If it bounces back, it’s probably done. Next, insert a toothpick into the center of the cake. If the skewer comes out clean or with just a crumb or two attached, the cake is done. If you’re testing a cake that has ingredients like chocolate in the batter, you should test the cake in several places; if you hit a puddle of molten chocolate your skewer might come out wet even when the cake is done.
Meat
Testing meat is a little more complicated because its temperature will continue to rise during the resting period, as much as 5 to 10 degrees, depending on the size of the piece of meat. (Larger roasts like standing rib roasts hold more heat and will continue to cook longer.) To make sure the meat doesn’t go past the target temperature after it rests, you need to take it out of the oven (or off the grill) a little before it’s done. That’s why in my recipes the recommended internal temperatures indicate the temperature you want before the meat rests under foil.
It’s important to note that guidelines for cooking meat have changed in recent years. At one-time people were afraid that rare or undercooked meat might carry diseases, particularly pork, which was associated with trichinosis. To ensure safety it had to be cooked to 180°F, which resulted in overcooked, dry meat. Now that trichinosis is no longer a danger, I cook pork to 137 or 140°F and it comes out rosy, moist, and delicious.
Beef: 125 to 130°F for medium rare
Chicken: 140 to 145°F for chicken breasts / 155 to 160°F for thighs or whole chickens
Pork: 137 to 140°F for medium rare
Lamb: 125°F for medium rare
Duck: 120°F for rare
Seafood
Seafood is generally judged for doneness by a visual test. Cooked fish will flake easily with a fork when it’s done, and shrimp will be just firm and pink. The exception is lobster, which should reach 140°F when tested in the tail with an instant-read thermometer.