[This bibliography contains only the more helpful commentaries on the Psalms and ones with which I am personally familiar. I have placed an * after those books that I would recommend you purchase.]
Allen, Ronald Barclay. Praise! A Matter of Life and Breath. Nashville: Thomas Nelson, 1980. *
Kidner, Derek. Psalms 1-72. Tyndale Old Testament Commentaries. Downers Grove: IVP, 1973.
Kidner, Derek. Psalms 73-150. Tyndale Old Testament Commentaries. Downers Grove: IVP, 1975.
Spurgeon, Charles H. The Treasury of David. 3 volumes. Grand Rapids: Zondervan, 1976. ***
VanGemeren, Willem A. Psalms. The Expositors Bible Commentary. Vol. 5. Grand Rapids: Zondervan, 1991. *
Williams, Donald. Psalms 1-72. Mastering the Old Testament. Dallas: Word Books, Publisher, 1986.
Williams, Donald. Psalms 73-150. Mastering the Old Testament. Dallas: Word Books, Publisher, 1987.
Wilson, Gerald H. Psalms Vol. 1. The NIV Application Commentary. Grand Rapids: Zondervan, 2002.
Survey Works on the Poetic/Wisdom Books
Aside from the many commentaries on the individual OT books, there are six introductions to the poetic/wisdom literature that are worthy of note:
Berry, Donald K. An Introduction to Wisdom and Poetry of the Old Testament. Nashville: Broadman & Holman Publishers, 1995.
Bullock, C. Hassell. An Introduction to the Old Testament Poetic Books. Chicago: Moody Press, 1988 [1979]. *
Bullock, C. Hassell. Encountering the Book of Psalms. Grand Rapids: Baker Academic, 2001. **
Crenshaw, J. L. Old Testament Wisdom: An Introduction. Atlanta: John Knox Press, 1981.
Kidner, Derek. The Wisdom of Proverbs, Job & Ecclesiastes. Downers Grove: IVP, 1985. *
Murphy, Roland E. The Tree of Life: An Exploration of Biblical Wisdom Literature. Grand Rapids: Wm. B. Eerdmans Publishing Co., 1996 [1990].