Suggested Reading
Allen, Leslie C. (2002) Psalms 101-150. 2nd ed. Word Biblical Commentary.
Berlin, A. (1992) The Dynamics of Biblical Parallelism. Indiana University Press.
Blaising, Craig A. & Carmen S. Hardin. (2008) Psalms 1-50. Ancient Christian Commentary on Scripture. IVP.
Craigie, P. (2005) Psalms 1-50. 2nd ed. Word Biblical Commentary.
Firth, D. (2006) Interpreting the Psalms: Issues And Approaches. InterVarsity Press
Futato, M. (2007) Interpreting the Psalms: An Exegetical Handbook. Handbook for Old Testament Exegesis. Kregel Academic & Professional.
Gerstenberger, E. (1988) Psalms: With an Introduction to Cultic Poetry Pt. 1: With an Introduction to Cultic Poetry. The Forms of the Old Testament Literature, Vol. 14. Eerdmans
Goldingay, J. (2006) Psalms, Vol. 1: Psalms 1-41. Baker Commentary on the Old Testament Wisdom and Psalms. Baker Academic
Goldingay, J. (2007) Psalms, Vol. 2: Psalms 2-89. Baker Commentary on the Old Testament Wisdom and Psalms. Baker Academic
Goldingay, J. (2008) Psalms, Vol. 3: Psalms 90-150. Baker Commentary on the Old Testament Wisdom and Psalms. Baker Academic
Grogan, G. (2008 ) Psalms. Two Horizons Old Testament Commentary. Eerdmans
Gunkel, H. (1998 ) An Introduction to the Psalms: The Genres of the Religious Lyric of Israel. Mercer Library of Biblical Studies. Mercer University Press.
Hossfeld, Frank-Lothar and Erich Zenger (2005) Psalms 2: A Commentary on Psalms 51-100. Hermeneia: A Critical and Historical Commentary on
the Bible. Augsburg Fortress
Kidner, D. (1981) Psalms 1-72. Tyndale Old Testament Commentaries. InterVarsity Press.
Kidner, D. (1981) Psalms 73-150. Tyndale Old Testament Commentaries. InterVarsity Press.
Kraus, H. J. (1986) Theology of the Psalms. Augsburg Fortress.
Kraus, H. J. (1987) Psalms: 1 – 59. Augsburg Fortress
Kraus, H. J. (1989) Psalms: 60 – 150. Augsburg Fortress
Kugel, J (1998 ) The Idea of Biblical Poetry: Parallelism and Its History, John Hopkins University Press.
Longman, T. (1988 ) How To Read the Psalms. IVP.
Mowinckel, S. (2004) The Psalms in Israel’s Worship. Eerdmans.
Tate, M. E. (1991) Psalms 51-100. Word Biblical Commentary.
Weiser, A. (2003) The Psalms. The Old Testament Library. Westminster John Knox Press.
Wesselschmidt, Q. F. (2007) Psalms 51-150. Ancient Christian Commentary on Scripture. IVP.
Wilson, G. H. (2002) Psalms Volume 1. NIVAC. Zondervan.
תהלים 
A nice list.
To get some flavor for recent holistic approaches to the Psalter, I would suggest the following:
Gerald Wilson, The Editing of the Hebrew Psalter, SBLDS.
Burnett, Bellinger, and Tucker, eds. Diachronic and Synchronic: Reading the Psalms in Real Time, LHB/OT 2007.
Bill Brown, Seeing the Psalms: A Theology of Metaphor
And two helpful introductions:
W.H. Bellinger, Jr., Psalms: Reading and Studying the Book of Praises (I am currently working with him on getting the second, revised edition of this out)
Nancy deClaisse-Walford, Introduction to the Psalms: A Song from Ancient Israel
Robert Alter’s The Art of Biblical Poetry is a helpful volume as well.
Yes, I need to update my list. Thanks for the suggestions!