Garth Nix... the Abhorsen series. (Starts with "Sabriel") This stuff is seriously good. It is written for children but is good enough for adults... and isn't even as kiddie-like as the Harry Potter series. Anything by this author is *wonderful*. And he's an Aussie! Necromancy for kids! Hooray!
I've mentioned this stuff before elsewhere, but I figure I should put it here, too....
The "Dark is Rising" series by Susan Cooper. This was the first "witchy" fiction I ever read... before I became a witch/whatever.

Great stuff. I may have to buy it again just so I can re-read it.
"So you want to be a Wizard" series, by Dianne Duane. I have some reservations about the "Book of Night with Moon" chapter in this series, since she vilified some good people, and knighted some historical villians.
(E. A. Budge was NOT a nice man. He was NOT a good archeologist. I could rant forever on this topic... sorry)
"Time Cat" by Lloyd Alexander. I admit, I have a soft spot in my heart for this book. It's an old classic from my childhood.
"The Sea Priestess"*, "Moon Magic" (sequel), "The Goatfoot God" "Demon Lover" "The Tales of Dr. Taverner"* are all good magickal fictional reads.
The starred ones are my favorites.
Oh, yeah, and I'm reading The Urban Shaman (A.K.A 'The Walker Papers') series by C. E. Murphy. High wierdness and high entertainment.
The first one is, predictably enough 'The Urban Shaman'.
I'm still kind of pissed at her (CE Murphy) for taking my idea (shaman/cop) and publishing before I did. Grrr.
OTOH, I should be cursing the name of The Sentinel too, I suppose. Sigh.
Carole endures. Sorta like The Dude.