It seems that many offer their suggestions for summer reading so I thought I would join the fray. My list will be short since the summer is half over.
Sensational Sins by John Piper
As always, Piper thinks long and hard about the text of Scripture and draws biblical conclusions. A great contribution to thinking "theodicy-cally."
Southern Baptist Theological Seminary, 1859-2009 by Gregory Wills
Very readable, don't let the thickness deter you. Interesting insights to the theological crisis in the post-Civil War South and the life of a denomination that recovered it's biblical roots with special focus on the last 50 years.
Portrait of Calvin by THL Parker
A rare, fun read on the life of perhaps the greatest (and most misunderstood) theologian/pastor since the NT. You can get it in PDF form from desiringgod.org
Horse Soldiers by Doug Stanton
A spell-binding account of the post-9/11 war in Afghanistan written like a novel.
The Greatest Game Ever Played by Mark Frost
Simply the most exciting sports book ever.