While logged in, go to http://wiki.tardis.ed.ac.uk/index.php?title=Special:Userlogin and you can create new accounts.

From… http://people.planetpostgresql.org/greg/index.php?/archives/74-Reset-a-user-password-on-MediaWiki.html. See also http://meta.wikimedia.org/wiki/Help:User_rights.

  mysql> insert into tw_user (user_name,user_real_name) values ('TestUser','Test User');
  Query OK, 1 row affected (0.03 sec)

  mysql> UPDATE tw_user SET user_password = md5( concat('25-',md5('somepassword'))) WHERE user_name='TestUser';

Where we really want the concat() call to be something like

  concat((SELECT user_id FROM tw_user WHERE user_name='TestUser'),'-',md5('somepassword'))

… Need to fix this and script this for a tardis-add-wikiuser script that users can run themselves to add their user or update password.