Those last three are great suggestions (I don't know #1). #2 is a classic, but I've read it a couple of times. #3 I've been meaning to read for years. #4 I'm actually in the middle of right now (I think because tptacek recommended it here) and unlike the vast majority of business books, it's superb. It's also older (pre-internet) which is actually a good thing as it focuses one's attention on fundamentals.