Querying Webservice API

Are there any Public WebService API that I can query and get t开发者_如何转开发he search results in XML?

There are plenty. One interesting place to explore might be Yahoo's YQL (Yahoo Query Language) service. That provides access to many several different APIs with an interesting interface, and will return results as XML (or JSON.)

YQL makes it very easy to write a "query" against one or more web service APIs that you can then use as a single HTTP GET-style request to return you XML.