If you have not had a chance to take a look at the new and improved home of the Lutheran Confessions on the Internet, BookofConcord.org, I think you will be interested in several new items we've added. Look for them under the "Sources and Context" section of the web site, in the left-hand column of the page.
Exsurge Domine, 1520
This Papal Bull set forth Rome's case against Luther and pointed out his perceived errors.
Excommunication of Luther, 1521
This is the actual Papal excommunication of Luther and all his followers, along with a photo of the document itself.
Johann Eck's 404 Theses, 1530
This document was, in large part, responsible for final content of the Augsburg Confession. Eck prepared this recounting of alleged heresies of Luther and other reformers, and his accusations were answered by the Augsburg Confession. It is a very interesting look into the mind of the Roman opponents of Luther. An excellent introduction and explanation by Henry Eyster Jacobs accompanies the translation.
Martin Luther's Exhortation to the Clergy in Augsburg, 1530
This was the first document that Luther prepared at his quarters at the Coburg Fortress, after his colleagues and the Lutheran princes went on to Augsburg, for the Diet. It has been called "Luther's Augsburg Confession." We have a few photos up of the Coburg Fortress and Luther's room there.
The Confutation of the Augsburg Confession, 1530
This was the Roman response to the Augsburg Confession, the document to which the Apology of the Augsburg Confession is replying.
The Consensus Tigurinus, 1549
John Calvin prepared this document as a statement intended to unify various strands in the Reformed movement. It conclusively demonstrates and proves that Calvinism is very much in favor of a spiritualizing interpretation of the Words of Institution and places Calvinism in the stream of Zwinglianism. Comments and expressions in this document are specifically repudiated by the Formula of Concord.
The Saxon Visitation Articles, 1592
The most concise and explicit rejection of Calvinism by Lutherans. These articles were prepared, and used, to rid Saxony of infiltrating Calvinists. It was included in all editions of the Book of Concord published in Germany, from 1592 until the Prussian Union of 1817.