A Practical Exposition upon Psalm 130
Both detailed and devotional, by Puritan minister John Owen.
Aquinas Translation Project: Psalms Commentary
[English, Latin] Niagara University's ongoing translation of "Commentary on the Psalms" by Thomas Aquinas.
Saint Augustine: The Psalms
An abridgment of the Latin original, this edition provides detailed exposition of each Psalm.
The Treasury of David
Originally a 7 volume commentary on Psalms written by Charles Haddon Spurgeon in the 1800's.