Our friends at MailChimp have made their eBook on User eXperience available for free:

At MailChimp, we love to show our work—partly because it makes us better at what we do. This ebook is a collection of the most popular articles from our UX Newsletter, along with some exclusive content. It embodies our quest to reflect, refine, and grow. We hope it’ll help you do the same. ~ MailChimp