case2

hey, I thought i'd post here and see if anyone can lead me in the right direction: I've currently got an idea for a site [top secert [img src=\"style_emoticons/[#EMO_DIR#]/smile.gif\" style=\"vertical-align:middle\" emoid=\":smile:\" border=\"0\" alt=\"smile.gif\" /] ] anyways basically I am stuck on one element - I want to have a way in which users can buy "virtual stamps", I figured a good way to do so is once a user pays via credit card, they will recive an e-mail, in this e-mail will be a random 4 digit code, thats their "virtual stamp". the reason a user needs a code is so they can upload their "package" to my server, I thought that with the upload form users select there file write there information etc.... and at the end they enter there e-mail and 4 digit code, and as long as the e-mail and code match in the database(MySql) the file processess Anyway has something like this been done ? any tutorials around that someone may know off ? Thanks!