The High Sierra: Peaks, Passes, and Trails - by R.J. Secor. Unquestionably the bible of California backcountry adventure. Reliable and exhaustive, which is no small feat, given the scale of the "Range of Light".

Hiking Yosemite National Park (FalconGuide) - The crowd pleaser. A cheap, "safe" general-interest text. Hey, that's a compliment!