RapidiOnline is Hosted at Internap, Atlanta http://www.internap.com/colocation-provider-facility-overview/colocation-data-center/ and we are using RailsMachine to provide us with a fully managed hosting http://railsmachine.com/

This combination gives us almost 100% uptime and 24 hours monitoring of our applications and processes (not just the servers) by some very well skilled people that are ready to act in a possible failure situation in order to get things running again as quickly as possible.