One that I got quite a bit from was William Bernstein's "Four Pillars of Investing." A 2nd edition came out this year with updates. Some interesting concepts such as deep vs shallow risk and fixed income investments that seem quite safe during good times but tend to deliver bad returns in bad times. Bernstein was a guest earlier this year on Morningstar's podcast "The Long View" for anyone interested in a preview of how he thinks about investing.