For the basics, Palmer's How to Brew can't be beat.
After that, Brewing Classing Styles.
Then, Designing Great Beers and Brew Like a Monk.
Those 4 will last you a good long while. From there, Radical Brewing and by that point you'll have been at it long enough to have an idea where to head.
Also, go to: http://www.thebrewingnetwork.com/shows/The-Jamil-Show
and go to the end. There's a free podcast on every basic style of beer; download the one you want to brew (if you're brewing a Sierra Nevada clone, grab the episode about American Pale Ales) and listen to it. That whole site and http://www.basicbrewing.com/index.php?page=radio
have lots of good free shows to listen to.
Finally, bookmark http://www.bjcp.org/2008styles/catdex.php
and refer back to it. It won't mean much at first, but as you get into things it's an invaluable resource.
On deck: Little Bo Pils, Bretta Off Dead (Brett pale)
Secondary: Oude Bruin, Red Sky at Morning (Sour brown ale)
On tap: Saison Duphunk (sour), Amarillo Slim (IPA), Earl White (ginger/bergamot wit)
Bottled: Number 8 (Belgian Strong Dark Ale), Eternale (Barleywine), Ancho Villa (Ancho/pasilla/chocolate/cinnamon RIS), Oak smoked porter (1/2 maple bourbon oaked, 1/2 apple brandy oaked)