The MSPA is the BBB of mystery shopping. This is an awesome resource for shoppers and mystery shopping companies. You can chat with other shoppers, search the job board, and locate companies to shop with.
"The MSPA is the largest professional trade association dedicated to improving service quality using anonymous resources. With over 150 member companies worldwide, our diverse membership includes marketing research and merchandising companies, private investigation firms, training organizations and companies that specialize in providing mystery shopping services. Our member companies work with their clients to establish mechanisms to measure and improve levels of service." Quoted from MSPA.
You can read about upcoming certification and events too.