http://www.cloudping.info/
For me (London) it looks like I could get a latency of 28ms if I hosted my rig in their Dublin datacenter, which sounds OK. (But obviously this would be on top of the ping to the multiplayer host, if you're playing online.)
This site has a much larger number of providers:
http://cloudharmony.com/speedtest-latency-for-compute-limit-...
But of course most of them don't offer GPU servers.
http://www.cloudping.info/
For me (London) it looks like I could get a latency of 28ms if I hosted my rig in their Dublin datacenter, which sounds OK. (But obviously this would be on top of the ping to the multiplayer host, if you're playing online.)