"Don't Make Me Think!" Second Edition, by Steve Krug
If you want new.
"The Simplicity Shift" By Scott Jenson
Not new, but will be useful for generations.
The Nielsen stuff is ageless. It will have useful information for ages.
The same goes for his partners; Bruce "Tog" Tognazzini and Donald A. Norman.
Don Norman's "The Design of Everyday Things" (Formerly "The Psychology of Everyday Things") is one of the best usability and design books I have ever read. It changed the way I look at the world, and will always be pertinent.
I would HIGHLY recommend against chasing "fads." If you want the latest techniques, then books won't be much help. You're better off perusing Web sites. Books tend to be out of date almost as soon as they hit the shelf.
The real core of usability and accessibility is timeless, and is based upon a deep understanding of what makes a site usable. You will need to make a lot of decisions, and Jakob Nielsen won't always have the best answer. You know your users and your corporate goals, so you need to make the best decision on a site-by-site basis.
You need to develop an internal "usability compass" that reflects your own values and that will permeate your work.
"We are what we repeatedly do. Excellence, then, is not an act, but a habit."