Route Via a Waypoint and Avoid a Country or SIGWX | RocketRoute
Guide to filing an IFR flight plan in ForeFlight - iPad Pilot News
I used Python and BTS data to create open-source route maps from 1999 and 2018 (see corresponding comment for clarifications + GitHub link) (updated with great circle lines and westbound trans-pacific routes) :
File a “Formation” Flight Plan | RocketRoute
Airline Route Map Images – Browse 15,200 Stock Photos, Vectors, and Video | Adobe Stock
XPFlightPlanner - How to generate a flight plan for X-Plane?