Since the Reformed Free Publishing Association (RFPA) is just one of several organizations committed to witness to the Reformed truth, here are several links to other organizations with the same purpose.
Protestant Reformed Churches in America
The Protestant Reformed Churches in America (PRCA) are dedicated to preaching and teaching the Reformed truth in the Calvinistic tradition. Much of the material published by the RFPA is written by the ministers and professors belonging to this denomination. Visit this site to learn more about the history, beliefs, and practices of the PRCA.

Sermon Audio 

The sermons posted here are a part of a collection of historical sermons called Heritage Recordings. Heritage Recordings are previously unpublished, historic sermons and lectures by several Protestant Reformed ministers. Many of these recordings provide a rare glimpse into the history of the PRCA in the mid-twentieth century—crucial years regarding the survival of the denomination. Some of them have their origin in the controversy regarding the nature of the covenant. All of them are a ringing exposition and defense of the sovereignty of God in the salvation of his people. All of these recordings have been digitally remastered for highest sound quality.
Reformed Witness Hour
The Reformed Witness Hour (RWH) is a radio broadcast program that has been proclaiming the truth of God’s word for over 60 years. The RWH program broadcasts on 20 stations throughout North America and also in Ireland and the Philippines. The current radio pastor, Rev. Carl Haak, is the pastor of Georgetown Protestant Reformed Church in Hudsonville, Michigan. Visit the RWH website for a list of radio stations that broadcast the program, as well as an archive of broadcasts from years past. 
Reformed Book Outlet
Reformed Book Outlet is a small non-profit bookstore in Hudsonville, MI, opened over 27 years ago.  It is a venture of three societies in our Hudsonville Protestant Reformed Church.  We strive to help those desiring dependable, worthwhile Reformed reading and who want to build good home libraries.  Along with books from many publishers, we carry a full selection of RFPA books, and try to stock titles reviewed in the Standard Bearer.  Any profits are used to produce and promote more Reformed literature.  The purpose of this venture is to be a witness of the Reformed faith, and especially to witness through our own Protestant Reformed literature. 
Covenant Protestant Reformed Church is located in Northern Ireland and is affiliated with the Protestant Reformed Churches in America. Covenant PRC is the main distributor for the RFPA throughout the United Kingdom and Europe. They also distribute pamphlets, audio sermons, and translations of several of the RFPA books in various languages.
The British Reformed Journal (BRJ) is the publication of the British Reformed Fellowship, usually with contribution from members, and currently published biannually. It contains doctrinal articles aimed at the propagation of the Reformed faith throughout the British Isles, Europe and abroad.

Beacon Lights 
The Beacon Lights is a Young People's magazine published monthly by the Federation of Protestant Reformed Young People's Societies. The magazine aims to: inform Christian young people about issues they face in today's world, connect Christian young people around the country and around the world, and to provide the light of God's word to all who read it.