What could be a great feature is a challenge based on existing on website kml files with ranking (scratch, by categories (elite, club, amator, beginner, master, senior, etc...)) with parents and children categories.
It would need for the visitor to be identified, with a profile where is set his category and first to ride one recorded by gps tools trail generating the same trail then compared on the website to the original track : time will be added to a permanent "live" timing challenge and ranking could be sorted by category.
I don't know neither if I'm clear enough, nor how to ?? (see timtoo concept)