I'll have to dig into learning about UART ports but I saw this board on Kickstarter and though it would be really nice if something this small and cheap would work for the task http://www.kickstarter.com/projects/digistump/digispark-the-tiny-arduino-enabled-usb-dev-board?ref=search
That board on kickstarter does not have enough pins and possibly not enough memory for your project. You need at least an Arduino Uno. If you make your own board, I would consider using a 1284P that CrossRoads has based some projects around.