1. Innovator's Dilemma and Innovator's Solution by Clayton Christensen
2. Built to Last and Good to Great by Jim Collins. Built to Last is more applicable for startups.
3. Mythical Man Month by Fred Brooks. Anyone who has to manage a team of programmers and hasn't read this will fail utterly, unless they've already failed before (or been on a failing team). There's a lot that's counterintuitive about software project management.
4. Peter Drucker's work. Kinda long and repetitive, but some good insights.
Marketing
1. All Marketers are Liars by Seth Godin. I like this better than Purple Cow, Guerilla Marketer's Handbook, and The Big Red Fez. Most of those have fairly obvious stuff.
Business & Management
1. Innovator's Dilemma and Innovator's Solution by Clayton Christensen
2. Built to Last and Good to Great by Jim Collins. Built to Last is more applicable for startups.
3. Mythical Man Month by Fred Brooks. Anyone who has to manage a team of programmers and hasn't read this will fail utterly, unless they've already failed before (or been on a failing team). There's a lot that's counterintuitive about software project management.
4. Peter Drucker's work. Kinda long and repetitive, but some good insights.
Marketing
1. All Marketers are Liars by Seth Godin. I like this better than Purple Cow, Guerilla Marketer's Handbook, and The Big Red Fez. Most of those have fairly obvious stuff.
2. The Tipping Point by Malcolm Gladwell
3. Crossing the Chasm by Geoffrey Moore
Technical
1. Building Scalable Websites by Cal Henderson
2. High Performance MySQL by Jeremy Zawodny
3. Pragmatic Programmer by...well, it's mentioned elsewhere here.
There are lots of other technical books I like, but most of them aren't directly relevant to the startup I'm building