I saw in a comment on Catherine's blog that the books in the store at Desiring God are on sale for $5! Check it out!
I have read and love: Desiring God, Faithful Women & Their Extraordinary God, and Let the Nations Be Glad!. I have The Pleasures of God but need to read it. Other books that friends have recommended include Brothers We are Not Professionals and Future Grace
Sale ends tomorrow. The functionality of the site is touch and go.
The sale was extended to noon on Friday, and the site is working much better today.