I just finished Von Neumann's War by Ringo & Taylor. A pretty good read. Doc Taylor wrote the book on defending against an alien invasion. (No, seriously...) It suffers a little bit from Doc Taylor's patented "Hey y'all, hold my beer and watch this!" approach to engineering, but that may just be my personal tastes on the subject.
Added bonus: the book turned me on to a group called The Cruxshadows. Here is the song mentioned in "Von Neumann's War". Citidel