This is a great piece of uer interface board, it is perfect for gaming and navigating through menu quickly. It has headers for LCD and Bluetooth modules.

Great! This Arduino Ethernet Shield that is based on the Wiznet W5100 Ethernet Chip gives you an easy way to get your Arduino Online. It is directly supported by Arduino official Ethernet Library.

The Wiznet W5100 provides a network (IP) stack capable of both TCP and UDP. It supports up to four simultaneous socket connections. Use the Ethernet library to write sketches which connect to the internet using the shield.

Note: This ethernet shield is not compatible with the Arduino Mega. It is compatible with Arduino Duemilanove (168 or 328). However, if you want to use it with the Arduino Mega, this tutorial shows you how to do so. More discussion about this topic can also be found here.

It has a regular size SD card slot that allows you to make a mini-server. This is our example code to get you started.

The Ethernet shield uses SPI interface. On the Arduino Duemilanove and other ATmega168 / 328-based boards, the SPI bus uses pins 10 (SS), 11 (MOSI), 12 (MISO), and 13 (SCK). On the Arduino Mega, this is 50 (MISO), 51 (MOSI), 52 (SCK), and 53 (SS). Note that even if you're not using the SS pin, it must remain set as an output; otherwise, the SPI interface can be put into slave mode, rendering the library inoperative.

Power on reset issue:

This is an issue with the Ethernet shield that when it is powered on, the reset button has to be pressed to get the Ethernet shield working. This issue is not specific on this Ethernet shield, but exists in all variant of the Arduino Ethernet shields. The issue is caused by the fact that the normal reset time of the Arduino is too short. Unfortunately this issue cannot be solved by software. Below are the solutions to resolve this problem, you may choose one in your preference.

1. Solder a 100 nF (or thereabout) capacitor between the reset pin and GND, the good place to put it is between the reset button of the Ethernet shield. However, by doing this, the Ethernet shield has to be removed from the Arduino while downloading the program to the Arduino, otherwise you will get the following error

avrdude: stk500_getsync(): not in sync: resp=0x00

2. Clip off the reset pin of the Ethernet shield, and connect it with a wire to an unused i/o of the Arduino. So the reset of the Ethernet shield is independent to the Arduino. Before calling the Ethernet library,  enable that output pin, pull it low for 100ms, and then switch the port back to input mode with pullups disabled.

This SD card is a little stunning add-on that is great for your project. It allows you to expand the non-volatile memory of your Arduino device to, well, a few Gigabytes as of the current technology.

It is equivalent to adding a hard drive to your Arduino device. This extra memory is essential for data logging applications, where data is normally needed to transfer to a pc for post-processing.

This SD card shield connected to the Arduino by SPI interface. Multiple devices can use the same SPI interface to communicate with the Arduino as long as each of the device has their own chip select.

It supports both regular size SD cards and micro-SD cards, but only one can be used at a time. A small prototyping area is available some prototype holds for user to expand their circuit on the shield. Photo shows the top and bottom views of the shield.

Features

• Arduino compatible 
• Stand SD card and MicroSD card compatible
• Prototype expand
• Arduino footprint expand
• Arduino Library support

When use the Standard SD card libriary in Arduino IDE, please change the CS pin from 4 to 10, i.e., change

SD.begin(4) to SD.begin(10)

If you are not sure, please just download and run this SD Card Shield example code.

Note: SDHC is not supported

Link to the Arduino SD card library

The Arduino Motorshield is the missing link for making a robot with the arduino. This Arduino Motorshield allows you to connect 2 DC motors and have total control of them from the arduino.

It allows you to move each DC motor
- Clockwise
- AntiClockwise
- Stall
- Control motor speed

This motor shield allows Arduino to drive two channel DC motors. It uses a L293P chip which
deliveries output current up to 2A each channel. The speed control is achieved through conventional PWM which can be obtained from Arduinos PWM output Pin 5 and 6.

Specs:
Peak Output Current (each Channel)
- Non Repetitive (t = 100ms): 3A
-Repetitive (80% on -20% off; ton = 10ms): 2.5A
-DC Operation: 2A
Analog voltage input: VIN 6.5-12V PWRIN 4.8-24V 
Digital voltage input: VD = 5V (7V max)
Max power dissipation: 25W

See  Motor Shield Tutorial for details of how to use it.

Cool projects you can do with this ethershield:

•  Read Google news from Arduino
•  Host a web page in the Arduino
•  Follow twitter messages of your friends, with no PC, But just a Arduino and Internet!!!!

This shield connects 2 powerful things The Arduino + The Internet = AWESOME!!!!!

The projects you can do with this shield is only limited by your imagination.

CD contains examples how to use it!! That way you get it going in a few minutes....

Note: This ethernet shield is not compatible with the Arduino Mega. It is compatible with Arduino Duemilanove (168 or 328). However, if you want to use it with the Arduino Mega, this tutorial shows you how to do so. More discussion about this topic can also be found here.