Lets see, oldest book?
Worlds Beyond, pub 1989. A small indy game with space exploration a percentile based character and rules system, but great charts for generating random star-systems and volumn based ship building.
Exalted Players Guide, Exalted: The Sidereal, and Dark Ages: Fae. Got them all at the same time. Saves on shipping.
I have all of the 2ed AD&D books plus three expansions for the monsterous manual. There is some weird stuff in those extra books. I also have the various players guides to the four basic classes, plus humanoids, and villians.
I also invested in 3.5ed through an online deal what wasnt bad. Gat all three core books, but not much past that.
All of the Exalted main books (Solar, Lunar, Abyssal, Sidereal, and Dragon-Blooded) as well as a few of the extra books. No caste or aspect books, not very interested in those.
Alot, and I mean alot of Vampire, Werewolf, Mage, Changeling, and Wraith. I've got most of the Year of the Lotus books (Book of 8 Million Dreams, Kindred of the East, Hengeyokai, etc) Also have all of the tribe books, a few tradition books and I love the Technocracy book.
I also have alot of Dark Ages books, including the Dark ages clan-books, and most of the core books as well. I get good bonuses at work.
Got a few 'other' books. Codex Tau, and Chaos Space Marines books, some indy game books rescued from a resale bin, Earthdawn, Shadowrun, some of that, some of this.
Ah, Battletech. I've got a few of those books, scenarios, technical read-outs, i've got all of those but the newest. Gotta love the Marauder evern though they stole it from Robotech. Havent touched any battletech in about three years though. Its just gotten silly.
That doesnt count any of the non-game books i have. There is alot of fiction, but also alot of historical, and factual works for inspiration, or trying to advance my writing career. Philosophy, mythology, herbology, coloring books, cook books, folktales and legends.
I am a bit of a bibliophile. Canya tell?