And people wonder why I wanted a database backend for CGI::Wiki. Earle was wondering about finding orphaned OpenGuides pages - pages that aren't linked to, aren't in any categories or locales, and aren't redirects. So I thought for a minute or two and wrote some (admittedly ugly and can probably be improved) SQL:
select distinct node.name from node left join internal_links on node.name=internal_links.link_to where internal_links.link_from is null and node.name not in (select distinct node from metadata where node in (select distinct node.name from node left join internal_links on node.name=internal_links.link_to where internal_links.link_from is null ) and metadata_type in ('category', 'locale') ) and node.text not like '%REDIRECT%';
and that does the job.