The R2Duino is a fully assembled USB stick sized Arduino clone based on the ATmega328P. It has the same functionality as the Arduino Nano 3.0, but comes in a different package. It lacks only a DC power jack, but has a standard size USB connector which fits right into the USB connector of your PC. The name R2Duino comes from the fact that this microcontroller board has 2 relays, connected to pins D8 and D9. The R2Duino was designed and is being produced by Certeza.

Specifications:

Microcontroller	Atmel ATmega328P
LEDs	Power Led, Programming Led (free to use for other solution)
Board & Schematic	Built to manufacturer's specifications Compatible with Arduino bootloader (already installed) Industrial temperature range -40∞ + 80∞ RoHs conform
Programming	ISP connector or Bootloader over USB
Operating Voltage (logic level)	5 V
Input Voltage (recommended)	via USB 5V or external 5V
Output Voltage (limits)	USB 5V and 3.3V
Maximal Total Current over USB:	500 mA
Digital I/O Pins	14 (of which 6 provide PWM output)
Analog Input Pins	8
DC Current per I/O Pin	40 mA
Flash Memory	32 KB (of which 2 KB used by bootloader)
SRAM	2 KB
EEPROM	1 KB
Clock Speed	16 MHz (Quarz)
Dimensions	70(L) x 24(W) x 15(H)mm
Extra	2 relays (60V AC/DC 400mA) on pins D8 and D9, enabled/disabled by jumpers
Extra	Standard size USB connector

Included in the package:
2 rows of pin headers. You can solder them on the board if you need them.

Datasheets:
R2Duino Schematic (pdf)
CPC1014N Relay datasheet (pdf)

Drivers:
USB CP210x Drivers for Windows, Linux, Mac (VCP Kit)