There are a lot of smart people and great services out there that help inform what we do. The common threads running through all of them is that they regularly provide high quality insights and independent thinking. Here are some of the sources that we consider most useful.

The Financial Times
The Financial Times is the grandaddy of the financial press. Characterized by terrific journalism, a global perspective, thoughtful editorials and excellent research, this is an essential component of any serious investment analyst. 

The Economist
Also characterized by terrific journalism, a global perspective, thoughtful editorials and excellent research, the Economist is arguably the single best way to stay on top of the most important happenings in the world. It has an uncanny way of revealing to readers the issues that become major headlines several months later.

Hussman Funds Weekly Market Comment
It is pretty clear after reading Hussman's lucid and analytically rigorous commentary that he was once a professor. Arete's Take is that he is one of the best thinkers in the business and if you are going to make a case against him, you had better have extremely good reasons for doing so. His weekly commentary is a must read.

Grants Interest Rate Observer
The Interest Rate Observer is a newsletter edited by the venerable Jim Grant for thirty years now. He focuses on fixed income and monetary issues and past editions contain some of the best insights available regarding the build up to and culmination of the financial crisis of 2008. More recently he has applied his considerable analytical skills to suggesting interesting stock ideas as well.

Zerohedge
You can find some of the best research on shadow banking, flash crashes, and wisdom from great investment thinkers at zero hedge. The price is having to filter through some conspiracy theories, but it is well worth the effort.

Mauldin Economics
John Mauldin has been around the markets for a long time and has built a commendable reputation for talking about the issues that few others dare to and for consistently providing independent thinking. His main newsletters Thoughts from the Frontline and Outside the Box are both free and filled with useful insights.

Epsilon Theory
Ben Hunt has significantly expanded his research offerings but his original Epsilon Theory note is still free and still the flagship for investment insights. Described as having a "worldview best understood through the lenses of history, game theory and philosophy", Hunt consistently provides the best insights into the increasingly politicized nature of capital markets and monetary policy.

Peak prosperity
Chris Martenson's background in science and special interest in teaching serve him well in Peak Prosperity's Crash Course, an incredibly useful, and accessible, seminar on economics, debt, the environment and how it all ties together. This should be required reading for all investors.

Federal Reserve Board of St. Louis (FRED)
Trying to make a point about how weak (or strong?) GDP growth has been the last several years? Look no further than FRED - an incredibly accessible amalgam of all the most important economic metrics combined with easy-to-use graphing tools. For the real geeks out there (and that includes us) there are also apps for your mobile devices.

Seeking alpha
While there is a great deal of research at Seeking alpha that is superficial or not well thought out, there are also a number of real gems and is a terrific source for transcribed earnings calls. It also contains a great deal of useful commentary.