The Art of Seduction - Robert Greene & Joost Elffers
This book is priceless for life advice. Understanding how to interact with people, primarily, but also understanding what others might be up to, as well.
My rating is low because it would appear that no one proofed this eBook before putting it on the iBook store. It doesn't affect the read too badly but it is slightly offensive to charge $16 for a version that wasn't very professionally proofed.