i was digging around in astalavista's membership source, and i happen to find some links that directed me to this page...
https://support.worldpay.com/downloads/index.html
click the search button as is.... for all available downloads.. they could be of some use maybe?
also world pay exploits there callback method
http://support.worldpay.com/kb/custo...ppcg_3003.html
and how to customize the results page...
http://support.worldpay.com/kb/custo...ppcg_3000.html
Again, these could be for learning from, or to help anyone's understanding with call backs and online purchasing...
enjoi
edit: In addition to this mumbo jumbo.. i have also discovered an index of a site which goes to explain some things of Telnet and other various texts under the folder "hacks"
http://www.morehouse.org/hin/blckcrwl/
I am unaware if these links had already been posted... if so feel free to remove this thread.
-regards