A Breakout Board for the MAX7219 LED Driver Chip from Maxim.
The MAX7219 is a cool LED driver chip for driving 7-segment led displays or a matrix of 8x8=64 leds. Unfortunately, the layout of the pins is terrible. With this pcb, you have the pins in a nice layout and one can easily access the pins. The pcb is chainable for the use of multiple MAX7219 chips. There is a good collection of sketches for the arduino, see link.