This tool miraculously recovered my data when the volume was unreadable and unfixable by the Disk Utility. The customer support rep from Prosoft was very helpful and responsive as well. This is well worth the investment.
An external drive wasn't mounting with some very important data inside. It would have been a disaster and spelled certain death with a new client if it wasn't recovered. Data Rescue was very easy to use and recovered everything with a simple scan. The software goes much deeper for harder-to-recover drives. I'm very glad I have it, because all hard drives fail eventually.