CSOs also known as Credit Service Organizations are unregulated companies that are now doing payday loans and other short term loans like auto title loans. It seems that with some recent payday loan regulations, there have been some that have been able to avoid the regulations because they are a CSO.  Credit service organizations offer payday loans and other short term type of loans without any limitations on fees they are charging the consumers.  However, they were initially created to help register our credit repair companies, not necessarily be a payday lender.  According to the dallasnews.com, “CSOs in Texas were originally established to control credit repair businesses; however, in the past few years, small-dollar lenders are operating as CSOs under a statutory loophole that allows them to obtain “an extension of consumer credit” for borrowers.”
Leadpile Lead Exchange works with all sorts of payday loan leads. These are all consumers that are looking for a short term fix to a temporary problem. Based on this article, CSOs are the ones that are doing some of the lending, not necessarily payday loan lenders per say.  Bottom line:  as a consumer understand any loan you ever take out and the fees associated with it.