On top of those suggested so far, I would add that "A Brief History of Everything" by Ken Wilber is an interesting read, and I second the suggestion on Zen and the Art of Motorcycle Maintainence. I think it sort of depends on whether you want books that serve as an intro to Philosophy as a formal subject, or if you want some books that deal with philosophy and make you think. I'd second the recommendation on Russel for formal-ish introduction.
ps. Concerning the stuff on Rand / Objectivism - funny : the first time I read Atlas Shrugged I thought it was awesome, but maybe long-winded a bit. The second time I thought it was more of a love story for nerds.
Either way, I think there are parts where you have to really plow through it...