Thought I'd start a thread on good books about space exploration. Are start with two books by Robert Zubrin that I have liked: The Case For Mars: The Plan to Settle the Red Planet and Why We Must Entering Space: Creating a Spacefaring Civilization And also a really nice website, intended for Sci-Fi writers, but it has excellent facts in it (there were occasional errors in it, but it is the best reference I have seen: http://www.projectrho.com/rocket/index.html
I know this isn't really about space exploration itself, but it explains a lot of common misconceptions while being an awesome read. Bad Astronomy by Phil Plait, who now has a thing on Discovery channel's website: http://blogs.discovermagazine.com/badastronomy/
I also read the Case for Mars and liked Robert Zubrin's plan for settling Mars. However, I can't help but feel that Zubrin is caught in a capitalist paradigm when explaining the reasons for going to Mars. A post-capitalist, post-scarcity society wouldn't need to go into space to acquire resources. The only remaining reason for settling space would be to ensure the continued survival of humanity, and this isn't a reason which motivates individuals. It would require a centralized authority to carry out space exploration and colonization. Private enterprise won't be enough.