I wrote up a client window selection example for VB.NET, it uses a crosshair to let you select a window and calculates your mouse coordinates relative to the selected window. You can download the source here: http://ibeblog.com/files/WndSelExampleVB.rar
RemObjects is the company that provided the Oxygene compiler technology that forms the base of Delphi Prism, the new Delphi.NET which integrates with Microsoft Visual Studio. They also have several products which rely a lot on sockets. To make things easier they built a custom library on top of the .NET socket library which contains a bunch of components which make it very easy to use sockets for various purposes. One of these components for example is the HttpClient component which lets you grab the contents of a webpage by simply calling it’s Get method and passing an URL to it. Next to this there’s also HttpServer, FtpClient, FtpServer and more! The components are included with Delphi Prism by default, but for those of you who use other Visual Studio languages it’s certainly recommended!
Find it here: http://www.remobjects.com/ip.aspx