Latest Arduino Uno, revision 3. This is the newest Arduino microcontroller board based on the ATmega328. Compared to Duemilanove, Uno has custom USB-to-serial chip based on ATMega8 which does not require any drivers to be installed. 100% compatible with previous Duemilanove.

It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

8-bit AVR Microcontroller with 32KB of Flash and 2kbytes RAM. Used in Arduino Duemilanove and Uno.

8-bit AVR Microcontroller with 8KB of Flash and 1024 bytes RAM, 3 PWM Outputs, 512 bytes EEPROM, 6 channels 10-bit ADC.

The LilyPad Arduino is a microcontroller board designed for wearables and e-textiles. Board consisting of an ATmega328 with the Arduino bootloader and a minimum number of external components to keep it as small as possible.

This shield gives the Arduino CAN-Bus capability. It uses the Microchip MCP2515 CAN controller with MCP2551 CAN transceiver. CAN connection is via a standard 9-way sub-D for use with OBDII cable.

The LilyPad Xbee board is a breakout board for the popular XBee modules. Board includes easy-to-sew tabs and all the necessary power regulation to run on the LilyPad system. Dimensions are 50mm outer diameter and very thin 0,8mm PCB.

LilyPad XBee was co-developed by Kate Hartman and Rob Faludi. It works with all the popular XBee module types but does not ship with a module.

Arduino Ethernet is a microcontroller board based on the ATmega328. It differs from other Arduino boards in that it does not have an onboard USB-to-serial driver chip, but has a Wiznet Ethernet interface. This is the same interface found on the Ethernet shield. An onboard microSD card reader, which can be used to store files for serving over the network, is accessible through the SD Library.

The Arduino ADK is a microcontroller board based on the ATmega2560 (datasheet). It has a USB host interface to connect with Android based phones, based on the MAX3421e IC. 

Arduino Power over Ethernet (PoE) Module is designed to extract power from a standard 802.3af PoE network provided by a switch or injector. Basically it lets you power your products on the end of a network cable without having to plug them into the wall.