I know you think this is a blog on value investing, but to know what you're doing investing in businesses, you need to know a lot about business. How else can you identify when a manager is pursuing a sound strategy, and when he's pissing into the wind? When I first started investing, I don't think I could tell the difference. Now, however, I think I can *sometimes* tell when a strategy is a poor one; though of course I could always be wrong. (The worst position to be in is where you're wrong, but "know" you're right...you have to be vigilant to ensure you avoid that where possible!)
To that end, I've been reading about strategies of how businesses should open new markets. This is a common problem faced by a number of companies under the value purview. Generally, these companies generate cash, but are cheap because Mr. Market sees no growth prospects for these firms. Managers of the companies, of course, often dispute such claims, arguing that they are on the cusp of opening new markets. Value investors would do well to understand when such a manager is wisely spending the firm's cash flow versus when he's throwing good money after bad.
The Entrepreneur's Guide To Customer Development is one of three books I've recently read on the topic of how new markets/segments should be grown so that resources are not needlessly wasted. (The other two are The Lean Startup and Four Steps to the Epiphany.)
The Entrepreneur's Guide is much more practical than the other two. I'd say it's more useful for actual managers involved in implementation. If you're running a new business, or growing a new segment within a larger business, I'd say this book is a must read.
If you're more interested in the concepts themselves and their justifications, I'd go with The Lean Startup, which is the book that really got me into the subject. The concepts don't just apply to startups; they can just as easily apply to established industries, such as life insurance companies or banks that are looking to innovate within their markets.