Old Post: I mention a few of my own recommendations below.
Doc Rampage is recommending books again, in response to Dean Esmay's post on great books no one's read. He mentions The Riddlemaster of Hed trilogy. By this point it's been mentioned so many times that it's pretty clear that plenty of people have read it. I agree that it's a great trilogy, and a significant inspiration for my own writing. It was the first fantasy series I read after Tolkien (must have been around fourth grade), and it's what convinced me that fantasy was worth reading--fantasy's been my primary reading material since then.
He also mentions a bunch of other series, only a few of which I've heard of and none of which I've read. Once again, more books are added to the list of Books I Really Should Read Once I Get Through the Ones I Already Have. It's a pretty long list by now.