37signals

Straightforward book on making sure a website user can get out of bind through well-categorized, to-the-point guidlines, supported by good and bad examples. Great as a design reference.

This book shows mostly through a long series of examples how to improve error messages and failure-point mitigation. While informative, I really don't think it was worth the price I paid for it. It was mostly screenshots with little in the way of explanations and information.

40 interesting and useful guidelines. The "Contingency Design Test" (pp. 220-7) is especially useful, although the score calculation seems rather unneccesary. Easy read, lots of illustrative (good as well as bad) examples.