In Mexico (via Reddit):
The Mexican Supreme Court of Justice on Thursday ruled that Wal-Mart de Mexico may not pay employees in part with vouchers redeemable only at its stores. The court nullified the employment contract of a worker who challenged the voucher payments, finding that they violated Article 123 of the Mexican Constitution, which guarantees the right to "dignified and socially useful work."
The sad part is, I could totally see conservatives justifying this kind of practice in the United States if they could get away with it. This is why regulations and "activist judges" are important.