I'd add Business @ The Speed of Thought by Bill Gates. Yeah, yeah, go ahead and laugh if you want.... It's a seriously interesting book. And this is coming from a guy who's a huge F/OSS ideologue and who really isn't a fan of Microsoft or billg. But I can give the Devil his due when necessary, and B@TSOT is a worthwhile read.

Of course, you might ask "Why, mindcrime, why do you recommend a billg book so highly?" Fair question... I find it interesting for the vision that Gates lays out regarding how organizations should use technology to operate more efficiently. He leaned heavily on the analogy with the human autonomic nervous system back in those days, and was throwing around the term "Digital Nervous System[1]" a lot... and I think that that concept A. makes and lot of sense, and B. is still - after all these years - largely unfulfilled.

If you're in the business of software (at least the business of business software) I think the Gates book is still very inspirational and could seed some very interesting ideas, vis-a-vis technology in organizations.

[1]: http://en.wikipedia.org/wiki/Digital_Nervous_System

Other than that, my own list would include:

The Art of the Start - Guy Kawasaki

The Four Steps to the Epiphany - Steve Blank

The Lean Startup - Eric Ries

Blue Ocean Strategy - W. Chan Kim and Renee Mauborgne

Crossing the Chasm - Geoffrey Moore

The 22 Immutable Laws of Marketing - Al Ries & Jack Trout

Positioning - Al Ries & Jack Trout

Repositioning - Jack Trout (with Steve Rivkin)

Differentiate or Die - Jack Trout (with Steve Rivkin)