These were some of the books which taught me a lot about Design were:

Don't make me Think by Steve Krug http://www.amazon.com/Dont-Make-Me-Think-Usability/dp/032134...

Non-Designer's Design Book http://www.amazon.com/Non-Designers-Design-Book-Typographic-...

Universal Principles of Design http://www.amazon.com/Universal-Principles-Design-Revised-Up...

Also make sure you go through design's everyday on Behance.net, they have some really amazing designers and design.