Don't Make Me Think
http://www.amazon.com/Dont-Make-Me-Think-Usability/dp/032134...
http://www.amazon.com/Dont-Make-Me-Think-Usability/dp/032134...
http://www.amazon.com/Emotional-Design-Love-Everyday-Things/...
Designing Interactions
http://www.amazon.com/Designing-Interactions-Bill-Moggridge/...