A total of 13 sites are hosted on 52.4.235.18.
Here are the first 5 as they would appear when searched for:
runkeeper.com/user/janinbangkok
(null)
runkeeper.com/user/rafek
(null)
runkeeper.com/user/637743672
(null)
runkeeper.com/user/215507188
(null)
runkeeper.com/user/hhulian
(null)
...and the list of the remaining 8:
runkeeper.com/user/cacimbao
runkeeper.com/user/maganet
runkeeper.com/user/hugopcosta
runkeeper.com/user/thaenzy
runkeeper.com/user/newmister
runkeeper.com/user/gogolev
runkeeper.com/user/pacokleiber
runkeeper.com/user/mbarrison