Being able to put your music catalog or video catalog online would be a nice feature.
I've been playing with an MP3Tag export script to put my CD catalog online. It exports an XML file along with my cover art. Then I'm working on some sort of web page to display the XML data nicely. MP3Tag makes it easy to do the export, but making it look good and be function is still up to you and some coding.
I think MC would be able to do the same using the
scripting plugin by Mr ChriZ, but I haven't looked into that scripting plugin yet. It would leave me at the same point I am with MP3Tag. Getting the data out is easy, making it formatted in a useful manner for a web page is the hard part.
An idea for MC might be an online catalog feature where you could have an online version of your collection with a URL to share with others. Music likes to be social and it's fun to share what music you have and/or like. An online catalog of your collection and selected playlists would allow you to share that info.