Microinteractions:Full Color Edition: Designing with Details, by Dan Saffer, talks about microinteractions – the small details of programs or sites.
These can be as small as a password verification widget that just tell you all the rules – instead of making you submit several times and mentioning one specific rule that you broke. Or Chrome's find tool showing every instance in the scrollbar. Every app is full of microinteractions.
The book goes through several interesting techniques on how to design these small details so that they are as useful as they can be. It also has plenty of great examples of smart microinteractions (some of which I have seen before, but never stopped to think about how clever they were before).
I really think reading this book will help my user interface design in the future. Very useful, short, and recommended to app designers.
As a quick note – the ebook version (MOBI, from O'Reilly) looks great on Kindle on an iPad.
