Asynchronous Socket Programming in C#: Part I
This is a simple Client-Server application developed to explain the concept of asynchronous sockets in C#. This extends the socket program to accept multiple clients. Because this example uses Asynchronous methods, threads are not necessary to communicate to multiple clients (though internally the asynchronous communication mechanism uses threads at the OS level).

.NET Web Services Tutorial
Writing .NET Web services without using Visual Studio can be tricky. Learn how to create a Web Service without using Visual Studio .NET.