May be it was asked or offered somewhere or else
But I would love to see such feature:
subscribe to the band and receive email(or at least here at website while visiting it) notifications when new album was added to the release list. To have a single source for tracking would be awesome

this would be awesome

This could lead to a lot of traffic.

Could be done like that:

user open http://www.metal-archives.com/bookmark
And those bands with new releases will be marked in some way, or will be put in the top of personal bookmarks or have some icon near their name, something like this

Probably could be just a minor change to bookmarks, yeah. Instead of (or in addition to) showing the last time the band was updated, show the last time a release was added. This could be either a new album, an older single or something you didn't know existed,a new version of an existing release, whatever.

I wouldn't want to burden HB and Morrigan with having to maintain a robust email server.