So I knew about this for a while, but didn't put it together that they would make for a nice library on your Nook. I haven't loaded any of these up, (I find Piper to be a bit tedious to read so I avoid him and let people tell me about what they read.) but since the Nook does such a good job with PDF's I figure they'd look decent.

All the books can be found here: Desiring God Resource Library

The list of available books:

• 50 Crucial Questions About Manhood and Womanhood


• Amazing Grace in the Life of William Wilberforce


• Beyond the Bounds


• Biblical Foundations for Manhood and Womanhood


• Can Our Differences Be Settled?


• Contending For Our All


• Counted Righteous in Christ


• The Dangerous Duty of Delight (Sample)


• Desiring God


• Do You Want a Friend?


• Don't Waste Your Life


• Faithful Women and Their Extraordinary God


• Fifty Reasons Why Jesus Came to Die


• Filling Up the Afflictions of Christ


• Finally Alive


• For Your Joy


• Future Grace (Sample)


• The Future of Justification


• God Is the Gospel


• God's Passion for His Glory


• A God-Entranced Vision of All Things


• A Godward Life (Sample)


• The Hidden Smile of God


• History's Most Spectacular Sin


• A Hunger for God


• In Our Joy


• The Innkeeper


• John Calvin and His Passion for the Majesty of God


• The Legacy of Sovereign Joy


• Life As a Vapor (Sample)


• The Misery of Job and the Mercy of God


• Most of All Jesus Love You


• Pierced by the Word


• The Pleasures of God (Sample)


• Portrait of Calvin


• The Power of Words and the Wonder of God


• The Prodigal's Sister


• Recovering Biblical Manhood and Womanhood


• Rethinking Retirement


• The Roots of Endurance


• Seeing and Savoring Jesus Christ


• Sex and the Supremacy of Christ


• Spectacular Sins and Their Global Purpose in the Glory of Christ


• Stand


• Suffering and the Sovereignty of God


• The Supremacy of Christ in a Postmodern World


• A Sweet and Bitter Providence


• The Momentary Marriage


• Treasuring God in Our Traditions


• Velvet Steel


• What Jesus Demands from the World


• What's the Difference


• When I Don't Desire God


• When the Darkness Will Not Lift


• Some of the books are translated into various languages

The biggest problem you may have is they appear to have formatting just like the print version, so the chapter heading is at the top of each page, and the page number at the bottom. There is also footnotes that aren't ePub style footnotes (just placed at the end of the page), so that may be bothersome as they'd interrupt the text.