I will be hosting a book giveaway for America's Romance With the English Garden (Thomas J. Mickey) in early June. It's apparently1 about the beginnings of the American garden industry, and how the English gardening style became the default style for American gardens. Not really normal PATSP fare, but it seemed like an interesting topic. If this interests you, you may wish to check out its page at Ohio University Press.
I've added another plant to my endorsed houseplant books in the sidebar: Tempting Tropicals: 175 Irresistible Indoor Plants (Ellen Zachos). It's more or less a general-purpose houseplant book, as opposed to the Griffith book, which aimed at commercial producers, so it's probably better suited to the average PATSP reader. The main thing I like about Tempting Tropicals as opposed to many of the other houseplant books I've looked at is, Zachos has better information than most of them. Instead of the usual short and fairly meaningless care instructions most houseplant books give you,2 Zachos actually goes into some detail, as well as providing more information about problems specific to each type of plant. There are other general houseplant books I approve of to one degree or another, but Zachos is the only one I would actually recommend to someone at the moment.3
I am also still technically working on my own book, or whatever it's going to be, though it's not going particularly well. The reasons for this may include but are not limited to: laziness, depression, poor time management, excessive physical exertion related to moving hundreds of plants in and out of the house and garage every time the weather changes, bad luck, not having a clear vision of the completed project, blogular interference, over-researching, declining enthusiasm for the subject matter, low self-esteem, or some combination of the above. But I am nevertheless still working on it. Technically.
2 E.g. "Light: Bright. Water: Keep evenly moist."
3 I have not received anything in exchange for this endorsement, and in fact don't actually even own a copy myself -- the copy I read, I got from the Iowa City Public Library.