Pastor Michael Phillips offers a nice overview in this MP3 of the Anabaptist movement, both the origin and early history of this group as well as an exploration of some of their key teachings. Speaking as an "anabaptist" (one twice baptized - once the wrong way as a little devil of a baby, once the right way as a professing believer) I really admire the convictions of the early believers who took a stand for their convictions, often with their lives sacrificed as a result.
Pastor Phillips talks about Conrad Grebel, a student of Zwingli in the 16th century. Zwingli was assailing the catholic mass at that time, as something not found in Scripture. Grebel took that a step further and applied that same reasoning logically to infant baptism as well. What is fascinating is that Zwingli privately agreed, yet hypocritically he publically supported paedobaptism. And sadly at that time it was the city council that stood in judgment over the matter, with Zwingli's backing, when truthfully Christ is the only head of the church. Grebel was arrested, imprisoned, but ultimately able to flee and continue to spread the word. The message also continues into details about Felix Manz and also Michael Sattler, the later who faced a brutal torture and execution simply because he taught and believed in the Scripturally-correct mode of baptism.
While the anabaptists were not without faults theologically, one of the interesting points made by Pastor Phillips is that, while there will be Judases in baptist churches, these are NOT ones that are deliberately brought in, whereas in the paedobaptising congregations, as he puts it in the message, the practice was that of "sprinkled water on the heads of little devils and brought into the church". Strong, true, but accurate.