Karl Barth for Preachers: A Bibliography
Karl Barth was arguably one of the best theologians of the twentieth century. His unique contributions to Protestant theology garnered interest from all parts of Christendom. Pope Pius XII (1876-1958) called Barth the most important theologian since Thomas Aquinas! By any measure, Karl Barth has had a profound influence on modern Christian leaders and scholars across a wide variety of traditions. He has had a tremendous impact on my own ministry. As a preacher, I'd love to see more teachers, preachers, and pastors draw upon the tremendous resources in Karl Barth's theology in order to improve their biblical and theological accuracy. But I'm aware that many seminaries do no expose pastors to Karl Barth's thought, and with the daunting size of his magnum opus, the Church Dogmatics, it might be easy to overlook Barth in your theological toolkit. However, this is a serious omission, one which is easily remedied if only you know the right places to start. Thus I've chosen some resources that I think are highly accessible and beneficial to the preachers and pastors among us--resources that have deeply impressed my own preaching and pastoral work.
If you are a preacher and would like some easy to access Barth resources that will benefit your preaching, I'd like to recommend the following:
First, his Evangelical Theology, a compilation of lectures delivered in 1962. Though Barth spoke German, they are in excellent English, were edited for quality though Barth's English is quite precise, and are a readable and exciting introduction to Barth's mature thought. Of these lectures, Eberhard Busch, the "dean" of Barth studies, writes, "At the end of his life, after writing so many theological masterworks, Karl Barth published an 'introduction' to evangelical theology.... Above all it demonstrates the serious joy of being a Christian theologian." As Eugene Peterson comments about the lectures, they are a work of "energetic brevity." Highly recommended. 
Second, I recommend Barth's commentary on that most ecumenical of Protestant catechisms, titled The Heidelberg Catechism for Today. You can also pick up a later release of this material titled Learning Jesus Christ Through the Heidelberg Catechism which contains very similar content. I offer catechism courses at our church for those aged 10 through high school. I teach from the Heidelberg Catechism (HC), and these reflections on the HC by Barth are invaluable. If the Heidelberg Catechism helps one see how the Christian faith applies to all of life, then Barth's commentary helps one see how Jesus Christ, through the lens of the HC, applies to all of life.
Third, Barth's The Faith of the Church: A Commentary on the Apostles' Creed According to Calvin's Catechism is an excellent interpretive version of the Apostle's Creed, through the lens of the Swiss Reformer John Calvin's catechism based upon it. Confused yet? This is Barth's take on Calvin's take on the Apostle's Creed, one of the foundational creeds of the Christian faith. I would highly recommend this volume to anyone, but especially to those who are interested in Barth studies and don't really know where to start. Due to its non-academic nature, this book provides a great introduction to a very dense thinker. It's also quite devotional, which is a plus, and can be read profitably as a pastor's own devotional material.
Fourth, I'd recommend Barth's Homiletics, a collections of lectures and seminars offered by Barth in which he reflects on how to prepare and preach sermons and how to interpret Scripture. Consider it a master class with the great theologian. Perhaps I should list this one first, but I think it important to understand Barth's thought and theology beforehand.
Finally, I'd highly recommend taking a look at the Church Dogmatics Index Volume: With Aids for the Preacher which is the index of resources meant to aid and resource the preaching pastor (if you have access to the Church Dogmatics). The index includes a Scripture and subject index to the Church Dogmatics (CD), an incredibly helpful way into the material of the CD, as well as a section of "Preacher's Aids" which have commentary sections of sermon reflections by Barth on the preaching lectionary. There's not a week that goes by that I don't use this reference in my own preaching work.
Of course, if you want, you could tackle reading the CD. Purchase of the Church Dogmatics is an investment, but an invaluable contribution to the preacher's library. If you are interested, I recommend reading my friend Dr. Kerry Magruder's excellent introduction to the work. I recommend purchasing the study edition. I have been on a multi-year writing project summarizing Barth's CD, and you can find these summary posts here. Even at the reasonable pace of 10 pages per day, you could read all of the volumes in about three years. This would be a tremendous blessing. At the very least, take a look at Barth's work on the doctrine of the Word of God, reconciliation, and election (his most unique contribution) if you want places to start which are not to be missed. There are excellent secondary works on Barth too, which would be profitable for the preacher.
 Busch and Peterson quotations retrieved from the back of the paperback edition of Evangelical Theology.