I kept this board as simple as possible. It just has the components needed to make the ATmega 328P-PU work. It has an ICSP connector to bootload the chip. So I can easily connect my USBasp to the board. To upload sketches I use an FTDI connector for which there is a header in the top left corner of the board. I used this design as a base for my other ATmega328 based designs.
Eagle board design: