There are a lot of great user experience books out right now. Some I've been able to get from the library, and some I've just wanted to have on my shelf for reference.
The stick figures in a previous post were inspired by Back of the Napkin (Dan Roam). This is the book that forced me to accept that I must improve my sketching. It's not written specifically for user experience people, but it explains cognitive psychology concepts in terrific plain language. It's full of examples relating to perception, encoding, and visualization. I highly recommend it if your come to user experience without a strong design background.
Measuring the User Experience (Tom Tullis, Bill Albert) is a good resource for practitioners who aren't well versed in making their user studies hold up statistically. As I posted previously, even if you're focused on qualitative usability test with small numbers of participants, it's important to be aware of what you're not testing. I certainly feel better knowing my chi-square from my confidence interval. The book also includes useful advice on judging nonverbal and emotional feedback from participants, and presenting results clearly to stakeholders.
Another new book with good focus on an important area is Moderating Usability Tests (Joseph Dumas, Beth Loring). Much of the material will be familiar to usability practitioners, but there are great tips inside even for old veterans of test facilitation.
I skimmed over the hefty, full color Designing Interactions (Bill Moggridge) in the bookstore, but it felt like a promotion for IDEO. Yes, they're the premier design consultancy, but how many of us can really do things the way they do? I did enjoy the end of the book, with artistic future explorations of how it might be to own meat-eating appliances and force your children to create hydrogen and power their share of the family.
Better, though I couldn't quite justify the purchase, was Designing for Interaction (Dan Saffer). This book presents hardware and even non-tech interaction design as well as that for software and the Web. It's a little slim for the price, and I would have liked more references so I could dig into the most interesting points.