MusicBee has regex functionality for virtual tags that can replace specific parts of the contents of a tag. ($RxReplace)
It could be useful to additionally have regex functionality that can just match a given regex.
Two examples where this could be useful:
The Musician Credits (TMCL) tag can contain all sorts of instrumentalists such as bass, drums, vocals, violin, etc.
Using a $RxMatch would allow to create a virtual tag that only contains the violin player, the guitar player, or perhaps the whole rhythm section. (bass, drums, rhythm guitar)
MusicBrainz offfers several 'identifiers' such as:
musicbrainz_artistid, musicbrainz_originalalbumid, musicbrainz_workid, _recordingcomment, _performance_attributes and many more.
(I believe there currently are at least 15 different ones)
Not to waste custom tags for each and every single one of them, you can concatenate them into one custom tag.
You can then extract the ones you want to use by using some nested splitting, but a regex could be better up for that task.
These are just two examples that came up thinking about this, but I am sure creative minds can come up with other useful purposes?
Thoughts?