I finished reading Programming Web Services with SOAP last month. I was rather disappointed, especially for an O'Reilly book. Some of the overview stuff was somewhat useful, but most of the code examples were way over my head.
My biggest problem was that the book was very much out of date. It was published in 2001, and is full of talk about not-yet-supported stuff. It would be really nice to see a second edition of this book, because the situation has surely changed in the last 8 years.
At the beginning of the year, I started fooling around with web services and SOAP.
Google offers a variety of Chart,Book Search and a Picasa API. Chart must be the simplest possible API out there: based on an image URL with a bunch of parameters, Google's server will create a custom image of a pie or bar or some other kind of chart. I haven't played with the other services yet, but they seem promising.
Xmethods offers a huge list of SOAP specific services, but many of the services offered are no longer in service, or just feel spammy. There are a few that seem promising though:
Other than the initial (and elementary) success with Google Charts, I've had a hard time working with SOAP. I'd really like some publicly available web services (that don't require registration) that I can use to request and recieve data? Can anyone suggest some?