This is akin to other requests for Social sharing. I appreciate that this could be a big ball of wax, and so as not to reinvent the wheel, you might want to create some app in conjunction with Facebook or other social networking site to handle the "who can see what" side of things.
I know I could export and share routes with friends, or send them the links for route ID's or post to Facebook, but it would be good to have a setting to simply include routes defined by friends in our own bookmarked routes list, or in the pulldown routes list in the workout log.
This is a terrific site, and I wish I'd found it ages ago. Thanks for everything that's already gone into it.