I liked "Getting Real". It sounds heavy (171 pages!) but it's laid out so you actually spend only like 15 seconds per page and its consumable in a few hours or so for the first run, and then you might want to go back and reflect at a later time.
Getting Real isn't a bible, obviously. As they say themselves, everything should always be taken with a grain of salt. Some stuff there is not applicable to all scenarios blah blah blah etc. But there is a lot in that book that I like. It says its about web applications, but a lot of it is about getting stuff (software) done and efficient teamwork in a broader sense. Old stuff such as "release early, release often", "work with few rockstars instead of many mediocres", "interdisciplinary people are good" etc are all put in the web context and into a coherent full package. It's a lot about avoiding bloat and bullshit bingo. YMMV, but I've found the best stuff (and any stuff at all, really) gets done when you cut the crap out of it and get short, sweet and to the point.
A theme that I liked was that "writing matters". As we become more global and impersonal, being able to write clearly in chats, e-mails and those places becomes more important.
A quote from the book.
Being a good writer is about more than words. Good writers know how to communicate. They make things easy to understand. They can put themselves in someone else’s shoes. They know what to omit. They think clearly.