Bill Bryson,
A Short History of Nearly Everything. It's a history of human reasoning, tracking the emergence of science into what we know today. Fills in a lot of meaningful gaps you may have forgotten from your various science courses, while providing the human side of major advances (rivalries, disappointments, hoaxes, all of it).
Science from a new perspective is excellent, but it's also such an interesting window on the many people who have struggled against really difficult problems to move humanity forward.
Also, make sure you go play Bioshock (the first one) for a sobering counterpoint on Randian thought. Atlas Shrugged is awesome, until you remember that you can't trust any group of people to maintain their rational behavior in the face of personal gains. Great story, and it'll drag you back from Randroid town (it did me, anyway). Either way, the kid in me would still love to have dinner in Galt's Gulch.
If you'd like to read eye-opening fiction, I heartily recommend The Moon is a Harsh Mistress, by Robert Heinlein. It's an incredible exploration of what it is to be free and how modern societies evolve at the expense of their citizens' personal liberties. One of the most thought-provoking pieces of fiction I've ever read, and lots of fun character-wise as well. (Incidentally, Heinlein was a fan of Ayn Rand, so if you liked Atlas Shrugged, you may find this even more interesting.)