Something I would like to see, is the possibility to do a mass change on all records / a subset of records.

Why? Well, I am planning on including some artist information on a separate page, and I would use one of the custom fields to contain the filename of that page. However, because it is only a few artists that I have information about, I would set that custom field to eg. "NONE.html" or something of the kind, ...
I guess you get the point...
I am sure this would have other usefull sides also.

Cheers,

Peter