To coin a marketing term from Microsoft, Web Service is about Integration and Interoperability, right?
Suppose that AnandTech wants to integrate the top 10 queries of "CPU" from Google into their main homepage. To do this, they call the Google Web Service. Google then executes the query on their server and returns the results in SOAP (XML) format. Then the AnandTech server parses the returned XML string and integrates the data nicely into the existing design of the homepage.
That's one example I can think of off the top of my head. It's also great for building portals that integrate information from all over the Internet.
Another cool one I've seen around was Microsoft's MapPoint Web Service. It'd be also cool if things like Yellowpages are accessible through Web Services.
Edit: About charging, I think that most of these services are designed for businesses any ways. So I think that cost is not an issue as long as it's reasonable for what they offer. Also, just because the Google Web Service is available, it doesn't mean that everybody has to use it either.
