Well if you understand how to use direct port manipulations then all you need is the below linked document that shows arduino pin mapping from/to arduino pin number to port.pin numbers of two of the popular arduino chip series. This can result in faster execution of sketches using I/O pins, but at the expensive of losing some portablity of the sketch between boards using different avr chips.
http://spreadsheets.google.com/pub?key=rtHw_R6eVL140KS9_G8GPkA&gid=0
Lefty