A training log much the same as Strava.com.. that would take data from gamin devices, nike+ devices, ect.
It would also have to do the similar stuff as mapmyrun.com , running2win.com , runningahead.com
It would show maps, graphs of what the user did.
The user will NOT have to use a device, that will be optional. If they didn't use a device, they will then be referred to a option much like runningahead.
Each user will have a profile, where they will be able to enter personal bests. They will be able to receive achievements. for accomplishing routes in the fastest time. There will achievements for beating a personal best in "x" distance.
There will be a leader board for the number of miles/kilometers run each week.
A functional forum where users will be able to communicate with one another. Profile picture a must. Ability to view other peoples profiles.
Strava.com - mapmyrun.com - unning2win.com - runningahead.com
all mixed into one.
Read the info on each of the websites listed above to better understand what to do.
Any questions, just ask me.