I love the idea of running clubs that welcome visitors from out of town. So, here is my very humble start at making a list. If anyone happens to read this, and knows of others, please post a comment or message me.
Los Angeles, California: Every Thursday Morning
The SoCal Coyotes running club hosts a morning run every Thursday at 6:10am. All levels of runners are welcome. The location changes from week to week, but it is always on a trail in West Los Angeles. Check the website, but also look at Facebook, which is often more up to date. The club also meets are Peets Coffee in Brentwood after the run.
Tokyo, Japan: Every Wednesday Night
Namban Rengo (roughly, "band of foreigners") holds workouts on an all weather track about half a mile from the Harujuku subway station in Toyko. All levels of runners are welcome. While runners are from all over the world, including Japan, conversation was almost all in English when I visited in late 2013. The club also goes out for dinner after the workouts.