I'll give a few suggestions that should cover a variety of interests.
1) Our Band Could be Your Life [http://www.amazon.com/Our-Band-Could-Your-Life/dp/0316787531/ref=sr_1_1?ie=UTF8&qid=1294110245&sr=8-1], Michael Azerrad:
This covers underground music, most of which are punk or derived from punk, from 1981-1991. If you're interested in that kind of music, it is a must-read. Each chapter is a profile on a different band during the period. It does a great job of capturing the motivations, the lifestyles, the creative processes, and the cultural significance of punk (I had no idea how persecuted some of the bands were, or how wretchedly poor some were).
2) Dickens. Specifically, A Tale of Two Cities. The opening of the book does some of the best construction of a zeitgeist ever in fiction. And to make things even sweeter, you can have it for free (yes, it is legal [http://www.gutenberg.org/ebooks/98]).
3) Slaughterhouse Five [http://www.amazon.com/Slaughterhouse-Five-Novel-Kurt-Vonnegut/dp/0385333846/ref=sr_1_1?s=books&ie=UTF8&qid=1294110971&sr=1-1], Kurt Vonnegut. Kurt Vonnegut is a personal hero of mine. This is my favorite book ever. It's in some ways autobiographical, as it deals with an event [http://en.wikipedia.org/wiki/Dresden_bombing] that Vonnegut experienced firsthand. His cognitive dissonance shows through the writing, which is what makes it so powerful to me. The world is lesser for his loss in 2008. But so it goes...
4) The Hitchhiker's Guide to the Galaxy [http://www.amazon.com/Hitchhikers-Guide-Galaxy-Deluxe-Anniversary/dp/1400052939/ref=ntt_at_ep_dpi_2], Douglas Adams. If I were to guess what would be the the most frequently recommended and referenced book on this website, this would be it. There's a good reason for that.
5) Into the Wild [http://www.amazon.com/Into-Wild-Jon-Krakauer/dp/0307387178/ref=sr_1_1?s=books&ie=UTF8&qid=1294111222&sr=1-1], Jon Krakauer. Yep, they made a movie about this a few years ago. It's good, but some things were changed and omitted. The book is another one of my favorites, because I can sympathize with McCandless and see how foolish he was at the same time. If you don't know the gist of it, Chris McCandless was a recent college graduate in the early 90s who abandoned what was his life to set out on a voyage to Alaska. He met a lot of people on the way and making an impact on their lives. I'll never stop debating myself on whether he was selfless or selfish, because he came into people's lives who ended up caring for him and he for them. But he was single-minded about what he wanted and left them worrying and not knowing what would happen to him.
I could go on, but I'll leave my last recommendation as not a book, but a website. Gutenberg [http://www.gutenberg.org/wiki/Main_Page] is a site that compiles books that have become public domain and stores them in formats you can read on your computer, e-reader, or you can print them out (Yikes at that paper usage). It's a noble endeavor, so check it out if you're into older books and not squeamish at the idea of reading a book on a computer.