Just my 2cents: have you read About Face ( http://www.amazon.fr/About-Face-Essentials-Interaction-Desig... ) In this book they explain a whole vision about computer things (memory, files, interfaces) that Apple is slowly implementing in tablets and Mac OS X (extending it with iCloud). I'm always pestering people at work with: "have you checked in the green book before doing this?"

Since Don't Make Me Think already came up, going to add About Face (have 2.0 but heard 3.0 is even better) http://www.amazon.com/About-Face-Essentials-Interaction-Desi...

and Design of Everyday Things http://www.amazon.com/Design-Everyday-Things-Donald-Norman/d...