I have an existing, functional website, commonrun.com, that I just launched last month. The site is intended to allow runners from cities throughout the country to plan, organize, and find group runs and/or races. From the homepage, users can click on their respective city, from there they can view all the runs happening in their area or post a run themselves to share. All runs are open, public invitations to connect and run (think meetup.com- but exclusively for running, and with a more localized focus). As the site gains exposure, I will look to monetize it by requiring race organizers to pay if they are posting races that cost money.
Please view the site, www.commonrun.com, and explore the post page with the needs I have stated in mind.