Amazon Light is a great example of the cool things you can do with web services and a good API. You can access Amazon via SOAP, http, XSLT, and a few other ways. I need to learn more about these things. They’re still at the magic stage for me.
UPDATE: he had to change it due to a cease and desist from Google, so it’s not Google-riffic anymore. It’s still small and fast and cool.