A typical way to develop perspective is to consider issues from different vantage points. A less common - but perhaps more valuable - way to develop perspective is to expose yourself to different ideas.
One way to do this is to read books that are at the fringes of your "typical" interest area - and then apply those concepts in your area of expertise and in your dealings with others. Here are some recent books that I have read, along with the interesting lessons that they taught:
Working the Room (Nick Morgan): If it is important enough to get up in front of a group and say something, then it is important enough to rehearse.
The Trusted Advisor (David Maister): Personal credibility and relationships are what develop long-term relationships with clients - not price.
Chaos (James Gleick): The seminal book on the origins and uses of Chaos theory; The biggest advances in science are often discovered by those whose training started in a different field. Conventional wisdom sometimes prevents progress.
Freakonomics (Steven Levitt/Stephen Dubner): Personal motivation and incentive are often at the heart of behavior.
Growing an Engaged Church (Albert Winseman): The connection between personal engagement and the development of a community of interest.
Getting to Yes (Roger Fisher /William Ury): Wear the other person's shoes: helping others get what they want is the first step to getting what you want.
Linked (Albert-Laszlo Barabasi): It's not the "nodes", but the connections between them that make the network.
Carpe Diem: How to become a latin lover (Harry Mount): This book is a description and primer on Latin; it illustrates what can be learned from a culture from it's language. (And conversely, how hard it is to learn about a culture if you don't know its language.)
Death Sentences (Don Watson): This book rails against the use of weasel words and management-speak.
Godel Escher Bach, an Eternal Golden Braid (Douglas Hofstadter): The intimate, and sometimes surprising, connection between philosophy, art, and music.
Leaving the Mother Ship and Personal Balance Sheet: More so than reading, writing about a subject in depth forces you to think deeply about it.
What's on your list - and what did you learn?