About that unified user database.
It would be most useful to see a table with a line for each email address and a column for each mailing list. Each cell would contain an 'enabled' checkbox, if they're on the list.
Beyond that, a database with a line per user and a list of their email addresses would be a wonderful enhancement.
We have 5 lists and only 20 people, and even with that small operation, it's a nightmare keeping track.