Eric has a RAID 5 server that has had two drives fail and he needs some data recovery services. Leo says he doesn't know if data recovery is even possible if more than one disc dies. If a large enough chunk of data was lost, there's just no way to get it back. But it will largely depend on how it failed. A controller could've gone bad, and that could be an easy fix and the data could still be there. This is why one backup isn't much of a backup.
As for a service, try DriveSavers. They do an excellent job. They're not cheap, but if anyone can get the data back, they can.