this is a python script to generate the default WPS pin for some routers i really don't know who wrote the original script but i thought i may share. Usage : python WPSpin.py 123456" where 123456 is the first or last 6 characters in the routers mac address.
you can download the script here

to use the pin with reaver use reaver -i [monitor divice] -b [router bssid] -p [wps pin]