Teensylu is a RepRap control board that is based on the very successful Sanguinololu design. The Atmel microcontroller has built-in USB and is preloaded with the LUFA CDC bootloader. This allows you to load the firmware straight from the Arduino IDE through the USB cable.
This board has all the features on it for operating a single extruder 3D printer with a heated bed. It provides one of the most compact and cost-effective controllers available.
Supplied with all necessary connectors
Other firmwares are currently untested but any firmware for an Arduino Mega should work with proper pin setup.
For instructions on how to load firmwares please visit Geetech's Wiki Page