Still need a Christmas present for a thoughtful Christian in your family or circle of friends? Let me suggest a few. On Sunday I mentioned John Owen's master-work equipping Christians to fight sin well: Overcoming Sin and Temptation. Similar, but more accessible, is Ralph Venning's The Sinfulness of Sin. Both are unparalleled in helping us understand sin, hate it and go after it to put it to death.
In the world of theology, some excellent books have been written this year. Two 2011 books I would highly recommend are Michael Horton's The Christian Faith. It is similar to Wayne Grudem's famous work but more integrated and personally written. Greg Beale also recently released A New Testament Biblical Theology. Beale's work, more than any other, has shaped my understanding of Revelation and how Old and New Testament eschatology fit together. I just started this book and am loving it.
Finally, if your friend loves books about the Cross and the gospel, let me recommend George Smeaton's The Apostle's Doctrine of the Atonement. Smeaton was a Scotch theologian in the 19th century and plumbed the depths of the atonement themes in the New Testament more than any other I've seen. If you don't take my recommendation for it, just consider that this is Jerry Bridges' favorite book. Enough said.