One my reading list right now is The Intelligent Investor by Ben Graham. See below for both the physical book and for the kindle ebook link from Amazon.
For those who don't know, Ben Graham is generally considered the father of value/fundamentals based investing. He was the teacher of Warren Buffett and taught him the underlying ideas of value investing which Buffett used to create his Berkshire empire. As Warren Buffett said of The Intelligent Investor: "the best book about investing ever written." While I also look at technical trading, fundamentals of a company is something you have to understand and use to really get the best return for the risk.
If you're going to read one book about real investing investing (as opposed to speculation/trading), you should read this one.