In the database, run the following query (via phpMyAdmin, for example)
Code:
SELECT DISTINCT vb_album.userid, vb_user.username
FROM vb_album
LEFT JOIN vb_user ON vb_album.userid = vb_user.userid
This will provide you with a result of userid/username of every user who has an album.
Note: vb_ is the table prefix in the sql code I gave you. If you don't have a prefix, remove that, or replace it with the prefix you use.