Billet banking, I can print it and pay on cash. I don't know if it is exclusively for Brazilian Steam users though..
These are all available payment methods on Steam: Credit / Debit Card PayPal WebMoney iDeal PaySafeCard Moneybookers Sofortüberweisung / DIRECTebanking.com Russian Terminals / Kiosks Wallet / In Game Transactions / Steam Gift Cards
Few of them accept direct-debit without bank accounts or scratch cards which you can buy in many places for cash. I don't think these payment methods are very popular though.