Aisquith Presbyterian Church in Parkville, Maryland, has an incredible archive of sermons by many well-known names such as Walter Kaiser, John Gerstner, James Boice, O. Palmer Robertson, and a trove of over 200 sermons by Dale Ralph Davis.
Robertson was an Old Testament giant. My introduction to him was through reading his excellent book Christ of the Covenants. Robertson was director of African Bible College in Uganda, and adjunct professor of Old Testament at Knox Theological Seminary. He has written many highly regarded books: Christ of the Prophets, The Genesis of Sex, The Psalms in Congregational Celebration, and The Israel of God.