Intertoobs. Intarwebs. Series of tubes. Whatever. Connect your Arduino / Freeduino SB to your LAN, WAN, or whole darn Internet!
Arduino is a great microcontroller platform, but if you want to work with it from afar, take a look at this shield - the Arduino Ethernet Shield.
It uses the Wiznet W5100 ethernet chip with internal 16K buffer, which gives you a network TCP/UDP stack, and will support up to four socket connections at the same time. And being an official Arduino product, the development environment has built-in Ethernet libraries for easy programming. There is also an onboard micro-SD card slot, which can be used to store files for serving over the network. It is compatible with the Arduino Uno and Mega (using the Ethernet library). The onboard microSD card reader is accessible through the SD Library. When working with this library, SS is on Pin 4.
A unique feature of this board is the use ofÂ long wire-wrap headers which extend through the shield. This passes the main Arduino pins straight through, allowing another shield to be mounted on top. Unfortunately, the Ethernet Shield needs the digital (SPI) pins 10, 11, 12, and 13, and needs dedicated access to these pins while the shield is being used.
Documentation and source files can be found Here