I  once stumbled on a webpage from world pay merchant.
that sites contains their list of customer using them
so u could click on a category and see the list of merchants there.
still looking 4 it.
any help/

I believe this is the page you seek:

Shop@WorldPay
http://www.shopatworldpay.com/

The page linked above enables you to select a category and find online
WorldPay shops who sell merchandise in that category. From the site:

"Welcome to Shop@WorldPay and thank you for visiting the shopping mall. 

Your shopping experience is based on departments with sub departments
within to help you find your way around the shopping mall. At any time
you can search for the item you want using the search facility or
navigate your way through departments as you browse around the shops."

I located the page after seeing this reference to it on a MasterCard site:

"At WorldPay's virtual mall, www.shopatworldpay.com, thousands of
retailers from around the globe are open for business, 24 hours a day,
seven days a week and searchable by category, name or location."

MasterCard International
http://www.mastercardintl.com/cgi-bin/newsroom.cgi?id=569 

I hope this helps! If this is not the correct page, please request
clarification so that I may resume the quest. If anything is unclear,
I'll be glad to offer further assistance before you rate my answer.

Best regards,
pinkfreud

excellent