There are couple of things that you need to make clear
But in a real disaster situation I would love to be prepared better. How do you manage this?
Dont wait for the disaster to happen. Taking backups is not just enough. You should be able to confirm that the backups you take are able to restore as well. A backup is good ONLY if you are able to restore it (and DBCC CHECKDB returns no corruption errors).
I tend to take my backups with CHECKSUM. To quote Paul Randal
using the WITH CHECKSUM option and having the backup complete successfully tells you that those pages with page checksums had not been corrupted by the I/O subsystem at the time the backup was taken.
Do you have a tool or anything which registers the newly created DB's?
Technically, you dont need a tool. All the new databases are in
master.sys.databases and msdb - backup tables record the backup history. The script from Paul Brewer - restore Gene takes care of generating the restore commands for you. (I have used it and its an excellent tool/script !)
If you really need to log what databases are created, then you can use server level trigger
CREATE_DATABASE and log it in a DBA database.