I've been ordering a lot of books lately.
Ariocarpus Etc: The Special, Smaller Genera of Mexican Cacti, John Pilbeam and Bill Weightman, BCSS
A Cactus Odyssey: Journeys in the Wilds of Bolivia, Peru, and Argentina, James D Mauseth, Roberto Kiesling and Carlos Ostolaza, Timber Press
The Native Cacti of California, Lyman Benson, Stanford University Press
Cactus of Arizona Field Guide, Nora and Rick Bowers and Stan Tekiela, Adventure Publications
Cacti of Texas: A Field Guide, A. Michael Powell, James F. Weedin and Shirley A. Powell, Texas Tech University Press
Cacti, Agaves, and Yuccas of California and Nevada, Stephen Ingram, Cachuma Press
Agaves of Continental North America, Howard Scott Gentry, The University of Arizona press
Lots of reading and study for when it's too darned hot to go out side this summer.
So far I have read A Cactus Odyssey and delved into Ariocarpus, Etc and both are highly recommended, despite some drawbacks. I decided to get The Cacti of Texas despite already having the more technical Cacti of the Trans-Pecos and Adjacent Regions, because the field guide seems more useful in the field. Go figure.
I wish someone would write a cactus flora of New Mexico.
Maybe over the summer or sometime I'll post some little reviews of some of these.