A few days ago I was recommended a book by one of my teacher friends that we both weren't told about in our music studies. He happened across it while doing some research for his project. It's called "What to Listen for In Music" by Aaron Copland. He was an American composer and originally published the book in the '30s and renewed it up into the '80s before his death. This is an excellent book if your just getting into figuring out theory or just want to figure out what you are listening to on the radio. It's a timeless book and written for the person with little background in theory. Check it out if you have some time.