A total of 13 sites are hosted on 52.2.152.254.
Here are the first 5 as they would appear when searched for:
runkeeper.com/user/maryanndana
(null)
runkeeper.com/user/GeorgeRuns
(null)
runkeeper.com/user/selmarunner
(null)
runkeeper.com/user/JoaoPio
(null)
runkeeper.com/user/jlatteri
(null)
...and the list of the remaining 8:
runkeeper.com/user/1241965632
runkeeper.com/user/728081002
runkeeper.com/user/StefanWestman
runkeeper.com/user/mijowe
runkeeper.com/user/hayyau
runkeeper.com/user/agoodchild
runkeeper.com/user/ieppin
runkeeper.com/user/dtran