As you can imagine, with my love of books and my love of architecture, I really love architecture books. This is a big genre in of itself and can be broken down into many categories -- there are technical books, glossy picture books, theory books, books for the layman, idea books, etc.
Archinect has a good architecture book listing collection (find it here). Their architecture books categories include education, reference, firms (i.e. monographs), criticism/theory, fiction, history, interiors, landscape, planning/urban design, technology, and web design. They even have an entire collection for Los Angeles.
There are so many architecture books out there, I find it very hard to shop for them online. I always love shopping at bookstores, since I love the tactile nature of a book, but for architecture books, its much more practical than that. With all those books, there is a whole lot of crap and sometimes its hard to tell online the difference between a good looking book and a poorly printed one.
Fortunately for me, there are some really great architecture bookstores in California. When I lived in LA, I shopped at Hennessey + Ingalls. Unfortunately, at the time, I was a student and had no money to be spending on books. They have a fantastic sales, though, which is when I did most of my shopping there. For those of you who prefer buying online, they do have a web store, in addition to their great bricks-and-mortar store.
Now that I'm in the SF Bay Area, I shop at the Berkeley branch of Builder's Booksource (they also have a SF store). When I am on 4th Street, I love stopping by just to see what's new. In addition to their great selection of glossy and "fun" books, they are also the go-to place for building codes (blech) and reference books.