It is a little project by @mstafford. You log activities on the site and it can take uploaded GPS data from various apps. There are charts to see who is most active in the various sports. I manage to make the top 5 in running and cycling, but that is only because there are not many people using it for now. I think it has some great potential. I know @Actifit has many more users and gives bigger votes, but I am interested in experimenting this what is out there. Exhaust seems to attract some serious athletes and not just people counting steps on the daily routine.