[vadimr]

What I ended up doing is creating a new usergroup and running a few SQL statements to put all users with 0 posts and url in signature or visitor messages into that group and then just using the built in prune users tool to wipe them out:

UPDATE user SET usergroupid=14 WHERE posts = 0 and lastactivity < UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 MONTH)) and userid = ANY (SELECT userid FROM `usertextfield` WHERE `signature` LIKE'%url%')

UPDATE user SET usergroupid=14 WHERE posts = 0 and lastactivity < UNIX_TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 MONTH)) and userid = ANY (SELECT userid FROM `visitormessage` WHERE `pagetext` LIKE'%url%')