I'd like to add another Fyodor Dostoevsky book Brothers Karamazov. It's an excellent book with a touch of mystery. Beautiful characterisations. A bit huge though.
Majority of the books comes to mind are personality development and self-help. Real book lovers should not limit only to the self-help books alone according to me
Well I am interested in knowing the books that are classics..like you shouldn't miss this book..that kind of books..well I am inclined more toward thrillers and fantasy.