The Arduino Prototyping Shield makes it easy for you to design custom circuits for your next Arduino project.
You can solder parts to the prototyping area to create your project, or use it with a small solderless breadboard (not included) to quickly test circuit ideas without having to solder. It's got extra connections for all of the Arduino I/O pins, and it's got space to mount through-hole and surface mount integrated circuits if you need to as well. It's a convenient way to make your custom circuit and Arduino into a single module.
Requires an Arduino board (not included)
Arduino 1.0 pinout
Large 0.1" prototyping area
Reset button
14 pin SMD footprint (50 mils pitch)
20 pin Trough Hole footprint (100 mils pitch)
SPI header
long and easy-to-solder ground / 5V rails
The 1.0 standard pinout consist in 4 additional pins: 2 of them placed near the AREF pin, that are used for TWI communication, and the other 2 are placed near the RESET pin. The IOREF pin is used to adapt the shield to the board on which is mounted. The last one is not connected and is reserved for future uses.
$16.99 
Schematic 