Sometimes we forget what the real purpose of all this fancy technology is. And what is that? To make our real lives easier. Mashups often help with that, allowing us to do such simple things as find a good beer, our favorite music artists, where the streetcars are, or where a park is.
It's always exciting to see those outside the web industry using an API to improve their sites. NY Times First Look blog has a great example of what Dallas Public Library has done with the Best Sellers API.