Questioning Extreme Programming by Pete McBreen
A useful analysis of the claims that the XP community makes and comparisons between the XP way and other Agile Methodologies. I'm currently about half way through and so far it seems like good stuff. It helps you understand what you can expect to gain from XP and if XP is the right thing for you. Often it wont be, but you may be able to learn something from it or use some aspect in your project anyway.
Selling the invisible by Harry Beckwith
Because I'd like more clients please ;) An 'Effective C++' approach to marketing a service company. The book contains lots of short items that help you realise what you might be doing wrong when you try and market a service.
C++ Gotchas by Stephen C. Dewhurst
Slack by Tom DeMarco
Excellent book. See full review here.