Daniel I. Block, Judges, Ruth (NAC) -- Must be handled with care. Caustic reading of Judges and Ruth.
Arthur E. Cundall and Leon Morris, Judges and Ruth -- Competent on the technical issues but finds a sub-Christian ethic in Old Testament law.
Dale Ralph Davis, Judges: Such a Great Salvation -- An incredibly helpful commentary for working with the overall themes of Judges and placing the book in a Christian context. Highly recommended for pastors and devotional reading.
Iain M. Duguid, Esther and Ruth -- Seemed to lack sympathy with the biblical characters.
Andrew Fausset, Judges -- A bit dated technically and some of the suggested applications tend toward allegory.
John R. Franke, Ancient Christian Commentary on Scripture: Joshua, Judges, Ruth, 1-2 Samuel -- Some helpful insights. Lots of lacunae from lack of historical comment.
John Gill, Deuteronomy to Kings -- Helpful background in rabbinical interpretation. Recommended.