I ran into a very interesting thread recently, where a posted had experienced a disaster. In this case, they had a SAN failure, where they lost a number of instances. There were backups of the master databases, but not backups of all the user databases. They wanted to try and determine which databases were on which instance, and which version of SQL Server to start the recovery process, trying to match up files to database and instances.
A true disaster. In fact, possibly an RGE, as Grant has named them. I hope this doesn’t happen to anyone in a production