While I sometimes wish something like this existed, it seems ripe for abuse and/or open to some sort of libel law violation should it get out of control.
Isn't it already explicitly illegal to post lists of customers who haven't paid in your store? IANAL, but I seem to remember that the case law is already pretty settled on this one.
IANAL, but having been previously affiliated with a company that did this, my understanding as far as general US law goes is that while it's illegal for collectors to name names, the original creditor can name and shame all he wants as long as he doesn't disclose truly private information ("This is the jerk's SSN!") and sticks to facts he can prove if a libel suit arises.
