Haven't read it yet, but just yesterday someone recommended this book to me: The Ten-Day MBA by Steven A. Silbiger. Supposed to provide a very practical coverage of business realities, despite the silly title.
I had never studied business before (at any level), but found myself in a position where I was managing software projects, and dealing with MBA's from our client companies every single day.
I wouldn't say this is a replacement for going to business school, but for me -- it helped me understand the world my clients were coming from, and how they were incentivized.
So yes -- very practical book, easy to get through, and highly recommended. Gives a broad overview of the field, so you can at least speak the lingo.