Tom Boyd made the ArduServer, a web server built in a Teensy that allows for remote control and the reading of sensors over the web.

The ArduServer uses a Teensy and a WIZ820 ethernet module.  The Teensy connects to an LED and light sensor.  Users can turn the LED on or off by using a web page.  The web page also displays reading from the light sensor and the state of the LED.    The LED and light sensor can be interchanged to other input/output devises such as temperature, photo sensor, etc.

The source code for the project can be found here.