His Dark Materials Trilogy (The Golden Compass, The Subtle Knife, The Amber Spyglass) by Phillip Pullman

The Hobbit & Lord of the Rings

The Farseer (The Assassin's Apprentice, Royal Assassin, The Assassin's Quest) & Tawny Man (Fool's Errand, Golden Fool, Fool's Fate) trilogies by Robin Hobb

Chronicles of Narnia

The Oz series (there's more than just the Wizard of Oz)

I've heard good things about but haven't read any of the Percy Jackson books and/or Eragon.

Yes the Percy Jackson series (Rick Riordan) and Christopher Paolini's Eragon series are excellent. You could also try Michael Scott's Alchemyst series. I have also heard that the Charlie Bone series is good.

Try Susan Cooper's THE DARK IS RISING series; one of its five volumes , THE GREY KING, won the Newbery in 1974.

I second the Oz series and Chronicles of Narnia.

There is also the new Hunger Games trilogy by Suzanne Collins.

Ender's Game by Orson Scott Card. It's a sci-fi story but it follows a brilliant boy who is trained to save the world. Excellent book.

Diane Duane's "Young Wizards" series, set in contemporary New York.

I agree the OZ series, Narnia Series, LOTR and the Dark is Rising are good for those who like HP.

The Pendragon Series by D.J Machale is excellent. About a 14 year old boy who is ripped from his fairytale, American dream life and sent hurtling through space and time on a mission to save not only his own world, but everything that ever was and ever would be. There are ten books, there is some lag to a couple books in the middle of the series, but you need to keep with them, because the last three books are amazing.

The Magician by Raymond Feist

I know how you feel ,read percy Jackson!