If interested in buying Hispanic history and Genealogy books, this will be the only website you will ever need. In their own words:
Founded in 1991, the Borderlands Book Store promotes awareness about the history of the Spanish and Portuguese Empires, Mexico and the Mexican Republic, the United States Borderlands and the genealogies of the Hispanic settlers of these areas.Specializing in Hispanic History and Genealogy. - www.borderlandsbooks.com
Let me just warn you all, books are pricey, (at least out of my budget) but I mainly use this website to browse whats out there and then I do search on World Cat to find the nearest library that may have it available.
Disclaimer: I am in no way or manner affiliated in any form or manner with this website, try out before you buy. Just wanted to share software that can be useful to any family historian or genealogist.