Funology: from usability to enjoyment.
A truly excellent collection of papers about the power and importance of fun, pleasure, and emotion in design. Here is an area in which the European researchers lead the way and this book, with three UK editors and one Dutch, puts together a mostly European cast of writers. Highly recommended: A great beginning for this most important and badly neglected area of research.
Unfortunately, this is published by an academic publisher who charges ridiculously high prices. And then they will wonder why the book doesn't sell, and probably raise the price even higher for the next book they publish because "these books don't sell well."