The Pursuit of Holiness by Jerry Bridges (currently reading)
Pursuing Holiness in the Lord by Jonathan Edwards
The Holiness of God by R. C. Sproul
Holiness by J. C. Ryle
Holiness Day by Day by Jerry Bridges
The Discipline of Grace by Jerry Bridges
Whiter than Snow: Meditations on Sin and Mercy by Paul David Tripp (currently reading)
I also think it's very important to read doctrine so I've decided to attempt to read through a couple of books on doctrine. You can follow a plan to read through the Institutes with others if you'd like. Here are the two that I want to begin working through in 2009.
The Institutes of the Christian Religion (2 Volumes) by John Calvin
What are your plans? What would you add to either list?