Here are some other books we bought, but these will actually be carried on the trail (not all at once). The databook covers the whole trail, listing everything from water supplies to road crossings. The larger guidebooks, broken down into 3 sections (southern CA, northern CA, and OR&WA), have detailed maps and trail descriptions.
Although we've both been hiking for years, we still have stuff to buy for this long distance hike. Here's our newest possession. Not the cat. That's Tigger, she's 13, and she's happy that we bought this GPS satellite messenger, so she (and our families) can follow our progress on the internet, and know that we're safe.