Here are some helpful resources that I have put together including favorite articles, favorite books, cool products, and useful calculators / tables.
Calculators, Tables, and Conversions:
Treadmill Pace and Incline Table. This table is great at helping you figure out what incline setting to use on a treadmill and for giving you a general idea of how difficult your workout was. It is not as precise as the calculator linked below, but it is simple and only takes a moment to use. I recommend printing and laminating a copy to leave on your treadmill.
Incline Calculator. This is a more robust version of the table linked above. This calculator allows you to enter in a specific speed, incline, and body weight. It then calculates the equivalent speed if you were to be running on flat ground. However, this calculator does not account for differences between indoor and outdoor running such as wind resistance. It only adjust for bodyweight and incline.
McMillan Running Calculator. If you don't want to pay for professional coaching, the tables here offer some of the best free advice you can find. You can enter your current and goal race times, then the calculator gives you suggested training paces for a variety of workouts. Since it doesn't have much data to work with, it has to make a lot of assumptions. For a typical runner, I find the suggested paces to be quite accurate, but it won't be ideal for everyone.
Vertical Feet Per Minute. This table shows your ascent rate at a variety of speeds and inclines. While ascent rate is correlated with effort / difficulty, it is not the only contributing factor. The less steep the incline, the more difficult it becomes to maintain a high ascent rate (think about it: you can't climb at all on flat ground, and imagine how long it would take to climb 1000 feet on 1% incline). However, many athletes still like to do workouts at fixed ascent rates, or know how long it would take to summit a particular peak at a certain speed/incline.
Using Lanes Other Than Lane 1 on the Track - like most runners, I naturally gravitate towards running in lane 1 when doing speed work on the track; the math is simple; 1 lap = 400m. But, running on the inside lane places more stress on the joints and is likely to cause injury if you run great distances on the track. I've lately been doing some marathon pace long runs the track and wanted to know exactly how many laps I needed to run in outer lanes, instead of relying on my Garmin. This calculator makes it simple. A conversion I like to remember: 12 laps in lane 3 is a 5k.
Find My Marathon - if you're a marathon runner, this website will help you find your next race and tell you what your goal time should be. Using weather data, elevation profiles, and other course information, this resource will convert your marathon time at one race to another. So if you ran a 3:02:30 at the Atlanta Marathon, it can tell you what you'll run the Boston Marathon in. It also has a cool pacing guide that takes elevation data and pacing strategy into account, rather than just spitting out even mile splits to follow. It has every marathon in the U.S. listed, so it is a great resource for planning your next race.
The Science of Running by Steve Magness - Not only is the book a fantastic read, but the website has tons of great content as well. This book provides an overview of current sport science and modern coaching techniques with discussion on what researches and coaches can learn from each other. If you want to learn more than just the basics, this will be one of your best resources.
The Hybrid Athlete by Alex Viada - If you are skeptical about concurrent training or don't believe it is possible to improve at strength sports and endurance sports simultaneously, this will be an eye opening read. This book discusses both the scientific background and practical application of concurrent training programs along with sample training templates.
Gear and Technology
Stryd Foot Pod - The only product of its kind on the market. This foot pod is unlike the one's manufactured by GPS watch companies. It's accuracy is unrivaled and it provides reliable power data (like a power meter for running) on a variety of terrain, indoors and out. Many major watches now offer special support for the Stryd foot pod, allowing you to pull speed/distance data from the foot pod while still recording GPS data points on the watch. I recommend using Stryd for speed/distance, then setting your watch to the least accurate GPS setting so that you can still get a map while conserving battery life. I recommend this product to all of my athletes who are willing to make the investment, especially those who regularly train indoors or on trails with poor satellite reception.
FellRrn - A wiki style page with in depth discussion on virtually any running related topic you can think of. Whether it's the basics of sport science, analysis for GPS or heart rate technology, or information on altitude training, this site is an extremely valuable resource. When I receive questions about gear or technology, I often direct people to this page.