Kilian Jornet - An absolute legend in the ultrarunning world.
Gary Robbins Runs - Lots of training insights for Gary's Barkley attempts.
Trail Sisters - Their mission is to increase women’s participation and opportunity in trail running through inspiration, education and empowerment.
Trail Runner Magazine - The authority on off road trail running.
iRunFar - A blog by Brian Powell, author of Relentless Forward Progress: A Guide to Running Ultramarathons
Trail & Kale - A comprehensive trail running blog with lots of product reviews.
Let me know your favourite trail running blogs in the comments. Feel free to plug your own blog.