I'd be curious to hear others' recommendations, but I've gotten a lot out of Good to Great, The Innovator's Dilemma, and Natural Capitalism.

If you're starting a startup, I'd recommend The Lean Startup over all of those, though.

To "do" business or to realize what you're stepping into?

If the latter, then The Fanciest Dive by Christopher M. Byron. OOP but worth getting.