This is a module I created in C# using Sockets and TCP.  Pressing the button will turn on my house lamp from any where in the world.  There are four parts to this application:

1. A client service installed on my local PC uploads and stores my IP address to a SQL server on da' net.   If the client service notices it's IP has changed, It updates the database.
2. A socket server app controlling phidgets and accepting TCP connections.  Once a connection is created, I parse the message and turn on my lamp via a relay switch.
3. A client on running here on this web page.  The client querys the database for my IP address first, and then creates a connection to my desktop.
4. The client here on this web page then sends a command to my socket server on my desktop that turns on my lamp.

Watched the video? Try it yourself:

Turn on my home lamp