One of the books I used to dream of writing was "a pattern language for the web." Well, now I don't have to: The Design of Sites: Patterns, Principles, and Processes for Crafting a Customer-Centered Web Experience is that book.

As I first sat down to read it, I didn't care for it. But sitting down and reading it not the right use for it-- instead leave it on your desk and as you approach any standard web element, from log-in box to global navigation bar, crack it open. The authors have done a masterful job of listing the key problems each element addresses, and shows examples from several "best practices" websites. It's like having a competive analysis on your desk for almost everything. Esoteric issues, like my current interest (entire-web search) are not addressed, but pretty much all the common ones are, and insightfully. An excellent tool for any IA, Interface or Interaction Designer.