Harry Potter, for certain. And the Middle Earth books, of course.

Neil Gaiman is a wonderful author, and I would recommend Neverwhere to anyone and everyone.

The Chronicles of Prydain by Lloyd Alexander. There was a movie made of The Black Cauldron years ago, but the series actually begins with The Book of Three.

Ursula K. Le Guin's Earthsea series.

The Howl's Moving Castle books by Diana Wynn Jones.

The Sword of Shannara series by Terry Brooks (soon to be a tv show!).

The Chronicles of Thomas Covenant is supposed to be good. I've only read the second book, The Illearth War, but the rest is supposed to be excellent. I believe Bleys is a big fan.

I've meant to read The Golden Compass, The Name of the Wind and The Dresden Files for a while.