You could use an HTTPRequest
<a href="http://msdn.microsoft.com/en-us/library/system.web.httprequest.aspx">http://msdn.microsoft.com/en-us/library/system.web.httprequest.aspx</a>[<a href="http://msdn.microsoft.com/en-us/library/system.web.httprequest.aspx" target="_blank" title="New Window">^</a>]
Though you are going to need to experiment a bit on how to pass custom params through.
Web services Is a completely different matter and it would be made for the expressed purpose of transfering result to an external application or website. Best is to approuch those sites ask them if they have such a service or is interest in , otherwise you are better off pulling the page data via a HTTPRequest
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