Right, since I'm a huge bibliophile, I figure I should make my mark here...
Anything by Dan Abnett is golden. Just utterly golden. Be it his Horus Heresy work, Gaunt's Ghosts, Eisenhorn, Ravenor, or his new Bequin trilogy. Though he works mostly in Science Fiction right now, and has even written a Doctor Who novel!
The Wheel of Time by Robert Jordan. Any Fantasy series that can strech for 13+ books and still captivate you is worth a look!
Dragonlance. It's one of the Fantasy classics! A must-read for anyone that likes fantasy and D&D.
The Deeds of Paksenarrion, by Elizabeth Moon. Three novels, but extremely well written, with a fantastic main character that draws you into the world of medieval mercenaries in a fantasy setting. A genuine page-turner.
The Night's Dawn Trilogy, by Peter F. Hamilton. And we're back in Sci-Fi country. This trilogy is very well written and exceedingly creative, and shows you just how weird human culture can become. But it's an adult's only series, as it shows sexual scenes between men and women, and hints at a bit of transexual as well, but nothing overt. It's also got some faintly disturbing themes at times, but it's a brilliant and quite fun series.
The Lord of the Rings by J.R.R. Tolkien. The Bible of the Fantasy lover. He created the modern Fantasy genre as we know it. He defined the Elves, Dwarves, and Halflings/Hobbits, as well as Orcs and Trolls, and told us just how wonderful the Medieval fantasy universe can be! A must-read for, well, anyone. The Fellowship of the Ring was the first novel I ever read, at the age of 12. And I've re-read the entire trilogy once a year.
Dune, by Frank Herbert. Sci-Fi's equivalent of Tolkien's Lord of the Rings. THE greatest Science Fiction series ever, (in my opinion of course), and all of it without even a single alien! It's a great novel, and a wonderful series. Political intrigue, plots within plots within plots, mystery, awe, and wonders.
I'll post here again when I can remember some more and taken a look at my library.