This recipe is from Fine Cooking. These are so buttery, crisp and delicious! The key to the crispness is the ratio of more white sugar than brown, the proportion of butter to the rest of the ingredients, and the fact that the butter and egg are at room temperature (the butter is soft).
Edited 5/22/06: I added tips in step 10 and 11 to help make sure they turn out thin and crispy. Another tip might be to warm the cookie sheet before adding the dough (I don't do this, though). Maybe the tips will help. As you can see in the picture, mine come out thin, and I think they're very buttery and crispy.
Chocolate chip cookies were first served at the Tollhouse Inn in Massachusetts.