I just finished off Designing For Emotion by Aarron Walter. Usually books from the Book Apart stable arre practical 'how to' guides, but the subject matter of this title makes it more of a theoretical affair. I won't go in to a full on book review, but here are the top points I marked in the book.
1: embedding personality in to your UX leads to customer loyalty. "Personalities foster friendship and serve as the platform for emotional connections.
2: Flickr used a simple competition to save an unplanned outage. "Though the site was down and many more were inconvienced, Flickr users remember the fun they had participating in the colouring contest, and for some, how great it was to win a free year of Pro service"
3: emotional design can act as insurance to product problems. "Emotional engagement can help us look past even the most serious infractions, leaving the good more prominent in our mind than the bad."