I'm confused too. Which programs or online databases do you want to use them with? And do you mean a simple report, or backing up the actual tags (allowing them to be re-applied to the music files)? The latter would be very tricky I would think.
There is an addon that backs up the tags that you specify in MM.db, but the exported data would only be compatible with Mediamonkey for restoration. viewtopic.php?f=2&t=42085