If you have an Arduino project and need a few extra pins have a look at the way that Mark from SpikenzieLabs did it. He removed the crystal and 22pf capacitors then he added a pin header to access the pins easily. To use this configuration you then need to set the fuses so that it uses the internal oscillator. The internal oscillator is not as accurate as the internal RC time constant but most applications aren’t time critical so this is normally not an issue.