Mike Oliphant's DDJ (Digital DJ) does most of this in concert with Grip and MySQL. This of course assumes you are running Linux. (edit:: I don't think it is as expandable as you'd like, but there's a new verion out -- haven't used it -- so thought it might be worth a look. When I used it, I used it with PHPMyAdmin to clean up entries, and I expect you could use that to add all the new fields you want.)